WebHelpers is a package designed to ease common tasks developers need that are usually done for formatting or displaying data in templates.
Helpers available by module:
webhelpers.date.distance_of_time_in_words(from_time, to_time=0, granularity='second', round=False)¶Return the absolute time-distance string for two datetime objects, ints or any combination you can dream of.
If times are integers, they are interpreted as seconds from now.
granularity dictates where the string calculation is stopped.
If set to seconds (default) you will receive the full string. If
another accuracy is supplied you will receive an approximation.
Available granularities are:
‘century’, ‘decade’, ‘year’, ‘month’, ‘day’, ‘hour’, ‘minute’,
‘second’
Setting round to true will increase the result by 1 if the fractional
value is greater than 50% of the granularity unit.
Examples:
>>> distance_of_time_in_words(86399, round=True, granularity='day')
'1 day'
>>> distance_of_time_in_words(86399, granularity='day')
'less than 1 day'
>>> distance_of_time_in_words(86399)
'23 hours, 59 minutes and 59 seconds'
>>> distance_of_time_in_words(datetime(2008,3,21, 16,34),
... datetime(2008,2,6,9,45))
'1 month, 15 days, 6 hours and 49 minutes'
>>> distance_of_time_in_words(datetime(2008,3,21, 16,34),
... datetime(2008,2,6,9,45), granularity='decade')
'less than 1 decade'
>>> distance_of_time_in_words(datetime(2008,3,21, 16,34),
... datetime(2008,2,6,9,45), granularity='second')
'1 month, 15 days, 6 hours and 49 minutes'
webhelpers.date.time_ago_in_words(from_time, granularity='second', round=False)¶Return approximate-time-distance string for from_time till now.
Same as distance_of_time_in_words but the endpoint is now.
Functions that convert from text markup languages to HTML
webhelpers.html.converters.markdown(text, markdown=None, **kwargs)¶Format the text to HTML with Markdown formatting.
Markdown is a wiki-like text markup language, originally written by John Gruber for Perl. The helper converts Markdown text to HTML.
There are at least two Python implementations of Markdown. Markdown <http://www.freewisdom.org/projects/python-markdown/>`_is the original port, and version 2.x contains extensions for footnotes, RSS, etc. Markdown2 is another port which claims to be faster and to handle edge cases better.
You can pass the desired Markdown module as the markdown
argument, or the helper will try to import markdown. If neither is
available, it will fall back to webhelpers.markdown, which is
Freewisdom’s Markdown 1.7 without extensions.
IMPORTANT:
If your source text is untrusted and may contain malicious HTML markup,
pass safe_mode="escape" to escape it, safe_mode="replace" to
replace it with a scolding message, or safe_mode="remove" to strip it.
webhelpers.html.converters.textilize(text, sanitize=False)¶Format the text to HTML with Textile formatting.
This function uses the PyTextile library which is included with WebHelpers.
Additionally, the output can be sanitized which will fix tags like <img />, <br /> and <hr /> for proper XHTML output.
Helpers that produce simple HTML tags.
Most helpers have an **attrs argument to specify additional HTML
attributes. A trailing underscore in the name will be deleted; this is
especially important for attributes that are identical to Python keywords;
e.g., class_. Some helpers handle certain keywords specially; these are
noted in the helpers’ docstrings.
To create your own custom tags, see webhelpers.html.builder.
A set of CSS styles complementing these helpers is in
webhelpers/public/stylesheets/webhelpers.css.
Create a check box.
Arguments:
name – the widget’s name.
value – the value to return to the application if the box is checked.
checked – true if the box should be initially checked.
label – a text label to display to the right of the box.
id is the HTML ID attribute, and should be passed as a keyword
argument. By default the ID is the same as the name filtered through
_make_safe_id_component(). Pass None to suppress the
ID attribute entirely.
The following HTML attributes may be set by keyword argument:
disabled - If true, checkbox will be grayed out.readonly - If true, the user will not be able to modify the checkbox.To arrange multiple checkboxes in a group, see webhelpers.containers.distribute().
Example:
>>> checkbox("hi")
literal(u'<input id="hi" name="hi" type="checkbox" value="1" />')
Output “</form>”.
Example:
>>> end_form()
literal(u'</form>')
Create a file upload field.
If you are using file uploads then you will also need to set the multipart option for the form.
Example:
>>> file('myfile')
literal(u'<input id="myfile" name="myfile" type="file" />')
An open tag for a form that will submit to url.
You must close the form yourself by calling end_form() or outputting
</form>.
Options:
methodmultiparthidden_fields.items() method if it has one, or just
iterating the object. (This will successfuly get multiple values for
the same key in WebOb MultiDict objects.)Because input tags must be placed in a block tag rather than directly inside the form, all hidden fields will be put in a ‘<div style=”display:none”>’. The style prevents the <div> from being displayed or affecting the layout.
Examples:
>>> form("/submit")
literal(u'<form action="/submit" method="post">')
>>> form("/submit", method="get")
literal(u'<form action="/submit" method="get">')
>>> form("/submit", method="put")
literal(u'<form action="/submit" method="post"><div style="display:none">\n<input name="_method" type="hidden" value="put" />\n</div>\n')
>>> form("/submit", "post", multipart=True)
literal(u'<form action="/submit" enctype="multipart/form-data" method="post">')
Changed in WebHelpers 1.0b2: add <div> and hidden_fields arg.
Changed in WebHelpers 1.2: don’t add an “id” attribute to hidden tags generated by this helper; they clash if there are multiple forms on the page.
Create a hidden field.
Create a password field.
Takes the same options as text().
Create a radio button.
Arguments:
name – the field’s name.
value – the value returned to the application if the button is
pressed.
checked – true if the button should be initially pressed.
label – a text label to display to the right of the button.
The id of the radio button will be set to the name + ‘_’ + value to
ensure its uniqueness. An id keyword arg overrides this. (Note
that this behavior is unique to the radio() helper.)
To arrange multiple radio buttons in a group, see webhelpers.containers.distribute().
Create a dropdown selection box.
name – the name of this control.selected_values – a string or list of strings or integers giving
the value(s) that should be preselected.options – an Options object or iterable of (value, label)
pairs. The label will be shown on the form; the option will be returned
to the application if that option is chosen. If you pass a string or int
instead of a 2-tuple, it will be used for both the value and the label.
If the value is a tuple or a list, it will be added as an optgroup,
with label as label.id is the HTML ID attribute, and should be passed as a keyword
argument. By default the ID is the same as the name. filtered through
_make_safe_id_component(). Pass None to suppress the
ID attribute entirely.
CAUTION: the old rails helper
options_for_selecthad the label first. The order was reversed because most real-life collections have the value first, including dicts of the form{value: label}. For those dicts you can simply passD.items()as this argument.HINT: You can sort options alphabetically by label via:
sorted(my_options, key=lambda x: x[1])
The following options may only be keyword arguments:
multiple – if true, this control will allow multipleprompt – if specified, an extra option will be prepended to the
list: (“”, prompt). This is intended for those “Please choose …”
pseudo-options. Its value is “”, equivalent to not making a selection.Any other keyword args will become HTML attributes for the <select>.
Examples (call, result):
>>> select("currency", "$", [["$", "Dollar"], ["DKK", "Kroner"]])
literal(u'<select id="currency" name="currency">\n<option selected="selected" value="$">Dollar</option>\n<option value="DKK">Kroner</option>\n</select>')
>>> select("cc", "MasterCard", [ "VISA", "MasterCard" ], id="cc", class_="blue")
literal(u'<select class="blue" id="cc" name="cc">\n<option value="VISA">VISA</option>\n<option selected="selected" value="MasterCard">MasterCard</option>\n</select>')
>>> select("cc", ["VISA", "Discover"], [ "VISA", "MasterCard", "Discover" ])
literal(u'<select id="cc" name="cc">\n<option selected="selected" value="VISA">VISA</option>\n<option value="MasterCard">MasterCard</option>\n<option selected="selected" value="Discover">Discover</option>\n</select>')
>>> select("currency", None, [["$", "Dollar"], ["DKK", "Kroner"]], prompt="Please choose ...")
literal(u'<select id="currency" name="currency">\n<option selected="selected" value="">Please choose ...</option>\n<option value="$">Dollar</option>\n<option value="DKK">Kroner</option>\n</select>')
>>> select("privacy", 3L, [(1, "Private"), (2, "Semi-public"), (3, "Public")])
literal(u'<select id="privacy" name="privacy">\n<option value="1">Private</option>\n<option value="2">Semi-public</option>\n<option selected="selected" value="3">Public</option>\n</select>')
>>> select("recipients", None, [([("u1", "User1"), ("u2", "User2")], "Users"), ([("g1", "Group1"), ("g2", "Group2")], "Groups")])
literal(u'<select id="recipients" name="recipients">\n<optgroup label="Users">\n<option value="u1">User1</option>\n<option value="u2">User2</option>\n</optgroup>\n<optgroup label="Groups">\n<option value="g1">Group1</option>\n<option value="g2">Group2</option>\n</optgroup>\n</select>')
Create a submit button with the text value as the caption.
Create a standard text field.
value is a string, the content of the text field.
id is the HTML ID attribute, and should be passed as a keyword
argument. By default the ID is the same as the name filtered through
_make_safe_id_component(). Pass None to suppress the
ID attribute entirely.
type is the input field type, normally “text”. You can override it
for HTML 5 input fields that don’t have their own helper; e.g.,
“search”, “email”, “date”.
Options:
disabled - If set to True, the user will not be able to usesize - The number of visible characters that will fit in themaxlength - The maximum number of characters that the browserThe remaining keyword args will be standard HTML attributes for the tag.
Example, a text input field:
>>> text("address")
literal(u'<input id="address" name="address" type="text" />')
HTML 5 example, a color picker:
>>> text("color", type="color")
literal(u'<input id="color" name="color" type="color" />')
Create a text input area.
Example:
>>> textarea("body", "", cols=25, rows=10)
literal(u'<textarea cols="25" id="body" name="body" rows="10"></textarea>')
A nice way to build a form for a database record.
ModelTags allows you to build a create/update form easily. (This is the C and U in CRUD.) The constructor takes a database record, which can be a SQLAlchemy mapped class, or any object with attributes or keys for the field values. Its methods shadow the the form field helpers, but it automatically fills in the value attribute based on the current value in the record. (It also knows about the ‘checked’ and ‘selected’ attributes for certain tags.)
You can also use the same form to input a new record. Pass None or
"" instead of a record, and it will set all the current values to a
default value, which is either the default keyword arg to the method, or
“” if not specified.
(Hint: in Pylons you can put mt = ModelTags(c.record) in your template,
and then if the record doesn’t exist you can either set c.record = None
or not set it at all. That’s because nonexistent c attributes resolve
to “” unless you’ve set config["pylons.strict_c"] = True. However,
having a c attribute that’s sometimes set and sometimes not is
arguably bad programming style.)
Create a ModelTags object.
record is the database record to lookup values in. It may be
any object with attributes or keys, including a SQLAlchemy mapped
instance. It may also be None or "" to indicate that a new
record is being created. (The class attribute undefined_values
tells which values indicate a new record.)
If use_keys is true, values will be looked up by key. If false
(default), values will be looked up by attribute.
date_format is a strftime-compatible string used by the .date
method. The default is American format (MM/DD/YYYY), which is
most often seen in text fields paired with popup calendars.
European format (DD/MM/YYYY) is “%d/%m/%Y”. ISO format (YYYY-MM-DD)
is “%Y-%m-%d”.
id_format is a formatting-operator format for the HTML ‘id’ attribute.
It should contain one “%s” where the tag’s name will be embedded.
Build a checkbox field.
The box will be initially checked if the value of the corresponding database field is true.
The submitted form value will be “1” if the box was checked. If the box is unchecked, no value will be submitted. (This is a downside of the standard checkbox tag.)
To display multiple checkboxes in a group, see webhelper.containers.distribute().
Same as text but format a date value into a date string.
The value can be a datetime.date, datetime.datetime, None, or “”. The former two are converted to a string using the date format passed to the constructor. The latter two are converted to “”.
If there’s no database record, consult keyword arg default. It it’s the string “today”, use todays’s date. Otherwise it can be any of the values allowed above. If no default is specified, the text field is initialized to “”.
Hint: you may wish to attach a Javascript calendar to the field.
Build a file upload field.
User agents may or may not respect the contents of the ‘value’ attribute.
Build a hidden HTML field.
Build a password field.
This is the same as a text box but the value will not be shown on the screen as the user types.
Build a radio button.
The radio button will initially be selected if the database value
equals checked_value. On form submission the value will be
checked_value if the button was selected, or "" otherwise.
In case of a ModelTags object that is created from scratch
(e.g. new_employee=ModelTags(None)) the option that should
be checked can be set by the ‘default’ parameter. As in:
new_employee.radio('status', checked_value=7, default=7)
The control’s ‘id’ attribute will be modified as follows:
"_", and remove any
non-alphanumeric characters except underscores and hyphens.To display multiple radio buttons in a group, see webhelper.containers.distribute().
Build a dropdown select box or list box.
See the select() function for the meaning of the arguments.
If the corresponding database value is not a list or tuple, it’s
wrapped in a one-element list. But if it’s “” or None, an empty
list is substituted. This is to accommodate multiselect lists, which
may have multiple values selected.
Build a text box.
Build a rectangular text area.
Create a hyperlink with the given text pointing to the URL.
If the label is None or empty, the URL will be used as the label.
This function does not modify the URL in any way. The label will be
escaped if it contains HTML markup. To prevent escaping, wrap the label
in a webhelpers.html.literal().
Same as link_to but return just the label if the condition is false.
This is useful in a menu when you don’t want the current option to be a
link. The condition will be something like:
actual_value != value_of_this_menu_item.
The opposite of link_to. Return just the label if the condition is
true.
Return an image tag for the specified source.
urlaltwidthheightpathpath if
possible. May not be specified if width or height is
specified. The results are also written to the debug log for
troubleshooting.use_pilwebhelpers.media.get_dimensions_pil or
webhelpers.media.get_dimensions is called. It has no effect if
path is not specified.Examples:
>>> image('/images/rss.png', 'rss syndication')
literal(u'<img alt="rss syndication" src="/images/rss.png" />')
>>> image('/images/xml.png', "")
literal(u'<img alt="" src="/images/xml.png" />')
>>> image("/images/icon.png", height=16, width=10, alt="Edit Entry")
literal(u'<img alt="Edit Entry" height="16" src="/images/icon.png" width="10" />')
>>> image("/icons/icon.gif", alt="Icon", width=16, height=16)
literal(u'<img alt="Icon" height="16" src="/icons/icon.gif" width="16" />')
>>> image("/icons/icon.gif", None, width=16)
literal(u'<img alt="" src="/icons/icon.gif" width="16" />')
Return a link tag allowing auto-detecting of RSS or ATOM feed.
The auto-detection of feed for the current page is only for browsers and news readers that support it.
urlfeed_typeExamples:
>>> auto_discovery_link('http://feed.com/feed.xml')
literal(u'<link href="http://feed.com/feed.xml" rel="alternate" title="RSS" type="application/rss+xml" />')
>>> auto_discovery_link('http://feed.com/feed.xml', feed_type='atom')
literal(u'<link href="http://feed.com/feed.xml" rel="alternate" title="ATOM" type="application/atom+xml" />')
>>> auto_discovery_link('app.rss', feed_type='atom', title='atom feed')
literal(u'<link href="app.rss" rel="alternate" title="atom feed" type="application/atom+xml" />')
>>> auto_discovery_link('/app.html', feed_type='text/html')
literal(u'<link href="/app.html" rel="alternate" title="" type="text/html" />')
Return script include tags for the specified javascript URLs.
urls should be the exact URLs desired. A previous version of this
helper added magic prefixes; this is no longer the case.
Specify the keyword argument defer=True to enable the script
defer attribute.
Examples:
>>> print javascript_link('/javascripts/prototype.js', '/other-javascripts/util.js')
<script src="/javascripts/prototype.js" type="text/javascript"></script>
<script src="/other-javascripts/util.js" type="text/javascript"></script>
>>> print javascript_link('/app.js', '/test/test.1.js')
<script src="/app.js" type="text/javascript"></script>
<script src="/test/test.1.js" type="text/javascript"></script>
Return CSS link tags for the specified stylesheet URLs.
urls should be the exact URLs desired. A previous version of this
helper added magic prefixes; this is no longer the case.
Examples:
>>> stylesheet_link('/stylesheets/style.css')
literal(u'<link href="/stylesheets/style.css" media="screen" rel="stylesheet" type="text/css" />')
>>> stylesheet_link('/stylesheets/dir/file.css', media='all')
literal(u'<link href="/stylesheets/dir/file.css" media="all" rel="stylesheet" type="text/css" />')
Convert boolean values into proper HTML attributes.
attrs is a dict of HTML attributes, which will be modified in
place.
bool_attrs is a list of attribute names.
For every element in bool_attrs, I look for a corresponding key in
attrs. If its value is true, I change the value to match the key.
For example, I convert selected=True into selected="selected". If
the value is false, I delete the key.
Powerful HTML helpers that produce more than just simple tags.
webhelpers.html.tools.auto_link(text, link='all', **href_attrs)¶Turn all urls and email addresses into clickable links.
linkhref_attrsExample:
>>> auto_link("Go to http://www.planetpython.com and say hello to guido@python.org")
literal(u'Go to <a href="http://www.planetpython.com">http://www.planetpython.com</a> and say hello to <a href="mailto:guido@python.org">guido@python.org</a>')
Generate a form containing a sole button that submits to
url.
Use this method instead of link_to for actions that do not have
the safe HTTP GET semantics implied by using a hypertext link.
The parameters are the same as for link_to. Any
html_attrs that you pass will be applied to the inner
input element. In particular, pass
disabled = True/False
as part of html_attrs to control whether the button is
disabled. The generated form element is given the class
‘button-to’, to which you can attach CSS styles for display
purposes.
The submit button itself will be displayed as an image if you
provide both type and src as followed:
type=’image’, src=’icon_delete.gif’
The src path should be the exact URL desired. A previous version of
this helper added magical prefixes but this is no longer the case.
Example 1:
# inside of controller for "feeds"
>> button_to("Edit", url(action='edit', id=3))
<form method="post" action="/feeds/edit/3" class="button-to">
<div><input value="Edit" type="submit" /></div>
</form>
Example 2:
>> button_to("Destroy", url(action='destroy', id=3),
.. method='DELETE')
<form method="POST" action="/feeds/destroy/3"
class="button-to">
<div>
<input type="hidden" name="_method" value="DELETE" />
<input value="Destroy" type="submit" />
</div>
</form>
Example 3:
# Button as an image.
>> button_to("Edit", url(action='edit', id=3), type='image',
.. src='icon_delete.gif')
<form method="POST" action="/feeds/edit/3" class="button-to">
<div><input alt="Edit" src="/images/icon_delete.gif"
type="image" value="Edit" /></div>
</form>
Note
This method generates HTML code that represents a form. Forms
are “block” content, which means that you should not try to
insert them into your HTML where only inline content is
expected. For example, you can legally insert a form inside of
a div or td element or in between p elements, but
not in the middle of a run of text, nor can you place a form
within another form.
(Bottom line: Always validate your HTML before going public.)
Changed in WebHelpers 1.2: Preserve case of “method” arg for XHTML compatibility. E.g., “POST” or “PUT” causes method=”POST”; “post” or “put” causes method=”post”.
webhelpers.html.tools.highlight(text, phrase, highlighter=None, case_sensitive=False, class_='highlight', **attrs)¶Highlight all occurrences of phrase in text.
This inserts “<strong class=”highlight”>…</strong>” around every occurrence.
Arguments:
text: phrase: highlighter:phrase must be a string if highlighter is
specified. Overrides class_ and attrs_ arguments.case_sensitive:phrase is a regex object.class_:**attrs:Changed in WebHelpers 1.0b2: new implementation using HTML builder.
Allow phrase to be list or regex. Deprecate highlighter and
change its default value to None. Add case_sensitive, class_,
and **attrs arguments.
webhelpers.html.tools.mail_to(email_address, name=None, cc=None, bcc=None, subject=None, body=None, replace_at=None, replace_dot=None, encode=None, **html_attrs)¶Create a link tag for starting an email to the specified
email_address.
This email_address is also used as the name of the link unless
name is specified. Additional HTML options, such as class or
id, can be passed in the html_attrs hash.
You can also make it difficult for spiders to harvest email address by obfuscating them.
Examples:
>>> mail_to("me@domain.com", "My email", encode = "javascript")
literal(u'<script type="text/javascript">\n//<![CDATA[\neval(unescape(\'%64%6f%63%75%6d%65%6e%74%2e%77%72%69%74%65%28%27%3c%61%20%68%72%65%66%3d%22%6d%61%69%6c%74%6f%3a%6d%65%40%64%6f%6d%61%69%6e%2e%63%6f%6d%22%3e%4d%79%20%65%6d%61%69%6c%3c%2f%61%3e%27%29%3b\'))\n//]]>\n</script>')
>>> mail_to("me@domain.com", "My email", encode = "hex")
literal(u'<a href="mailto:%6d%65@%64%6f%6d%61%69%6e.%63%6f%6d">My email</a>')
You can also specify the cc address, bcc address, subject, and body
parts of the message header to create a complex e-mail using the
corresponding cc, bcc, subject, and body keyword
arguments. Each of these options are URI escaped and then appended
to the email_address before being output. Be aware that
javascript keywords will not be escaped and may break this feature
when encoding with javascript.
Examples:
>>> mail_to("me@domain.com", "My email", cc="ccaddress@domain.com", bcc="bccaddress@domain.com", subject="This is an example email", body= "This is the body of the message.")
literal(u'<a href="mailto:me@domain.com?cc=ccaddress%40domain.com&bcc=bccaddress%40domain.com&subject=This%20is%20an%20example%20email&body=This%20is%20the%20body%20of%20the%20message.">My email</a>')
webhelpers.html.tools.strip_links(text)¶Strip link tags from text leaving just the link label.
Example:
>>> strip_links('<a href="something">else</a>')
'else'
The MIMEType helper assists in delivering appropriate content types for a single action in a controller, based on several requirements:
If the URL ends in an extension, the mime-type associated with that is given the highest preference. Since some browsers fail to properly set their Accept headers to indicate they should be served HTML, the next check looks to see if its at least in the list. This way those browsers will still get the HTML they are expecting.
Finally, if the client didn’t include an extension, and doesn’t have HTML in the list of Accept headers, than the desired mime-type is returned if the server can send it.
webhelpers.mimehelper.MIMETypes(environ)¶MIMETypes registration mapping
The MIMETypes object class provides a single point to hold onto all the registered mimetypes, and their association extensions. It’s used by the mimetypes method to determine the appropriate content type to return to a client.
add_alias(alias, mimetype)¶Create a MIMEType alias to a full mimetype.
Examples:
add_alias('html', 'text/html')add_alias('xml', 'application/xml')An alias may not contain the / character.
init()¶Loads a default mapping of extensions and mimetypes
These are suitable for most web applications by default. Additional types can be added by using the mimetypes module.
mimetype(content_type)¶Check the PATH_INFO of the current request and client’s HTTP Accept to attempt to use the appropriate mime-type.
If a content-type is matched, return the appropriate response
content type, and if running under Pylons, set the response content
type directly. If a content-type is not matched, return False.
This works best with URLs that end in extensions that differentiate
content-type. Examples: http://example.com/example,
http://example.com/example.xml, http://example.com/example.csv
Since browsers generally allow for any content-type, but should be sent HTML when possible, the html mimetype check should always come first, as shown in the example below.
Example:
# some code likely in environment.py
MIMETypes.init()
MIMETypes.add_alias('html', 'text/html')
MIMETypes.add_alias('xml', 'application/xml')
MIMETypes.add_alias('csv', 'text/csv')
# code in a Pylons controller
def someaction(self):
# prepare a bunch of data
# ......
# prepare MIMETypes object
m = MIMETypes(request.environ)
if m.mimetype('html'):
return render('/some/template.html')
elif m.mimetype('atom'):
return render('/some/xml_template.xml')
elif m.mimetype('csv'):
# write the data to a csv file
return csvfile
else:
abort(404)
# Code in a non-Pylons controller.
m = MIMETypes(environ)
response_type = m.mimetype('html')
# ``response_type`` is a MIME type or ``False``.
Number formatting and calculation helpers.
webhelpers.number.format_number(n, thousands=', ', decimal='.')¶Format a number with a thousands separator and decimal delimiter.
n may be an int, long, float, or numeric string.
thousands is a separator to put after each thousand.
decimal is the delimiter to put before the fractional portion if any.
The default style has a thousands comma and decimal point per American usage:
>>> format_number(1234567.89)
'1,234,567.89'
>>> format_number(123456)
'123,456'
>>> format_number(-123)
'-123'
Various European and international styles are also possible:
>>> format_number(1234567.89, " ")
'1 234 567.89'
>>> format_number(1234567.89, " ", ",")
'1 234 567,89'
>>> format_number(1234567.89, ".", ",")
'1.234.567,89'
webhelpers.number.mean(r)¶Return the mean (i.e., average) of a sequence of numbers.
>>> mean([5, 10])
7.5
webhelpers.number.median(r)¶Return the median of an iterable of numbers.
The median is the point at which half the numbers are lower than it and half the numbers are higher. This gives a better sense of the majority level than the mean (average) does, because the mean can be skewed by a few extreme numbers at either end. For instance, say you want to calculate the typical household income in a community and you’ve sampled four households:
>>> incomes = [18000] # Fast food crew
>>> incomes.append(24000) # Janitor
>>> incomes.append(32000) # Journeyman
>>> incomes.append(44000) # Experienced journeyman
>>> incomes.append(67000) # Manager
>>> incomes.append(9999999) # Bill Gates
>>> median(incomes)
49500.0
>>> mean(incomes)
1697499.8333333333
The median here is somewhat close to the majority of incomes, while the mean is far from anybody’s income.
This implementation makes a temporary list of all numbers in memory.
webhelpers.number.percent_of(part, whole)¶What percent of whole is part?
>>> percent_of(5, 100)
5.0
>>> percent_of(13, 26)
50.0
webhelpers.number.standard_deviation(r, sample=True)¶Standard deviation.
From the Python Cookbook. Population mode contributed by Lorenzo Catucci.
Standard deviation shows the variability within a sequence of numbers. A small standard deviation means the numbers are close to each other. A large standard deviation shows they are widely different. In fact it shows how far the numbers tend to deviate from the average. This can be used to detect whether the average has been skewed by a few extremely high or extremely low values.
Most natural and random phenomena follow the normal distribution (aka the bell curve), which says that most values are close to average but a few are extreme. E.g., most people are close to 5‘9” tall but a few are very tall or very short. If the data does follow the bell curve, 68% of the values will be within 1 standard deviation (stdev) of the average, and 95% will be within 2 standard deviations. So a university professor grading exams on a curve might give a “C” (mediocre) grade to students within 1 stdev of the average score, “B” (better than average) to those within 2 stdevs above, and “A” (perfect) to the 0.25% higher than 2 stdevs. Those between 1 and 2 stdevs below get a “D” (poor), and those below 2 stdevs… we won’t talk about them.
By default the helper computes the unbiased estimate for the population standard deviation, by applying an unbiasing factor of sqrt(N/(N-1)).
If you’d rather have the function compute the population standard
deviation, pass sample=False.
The following examples are taken from Wikipedia. http://en.wikipedia.org/wiki/Standard_deviation
>>> standard_deviation([0, 0, 14, 14]) # doctest: +ELLIPSIS
8.082903768654761...
>>> standard_deviation([0, 6, 8, 14]) # doctest: +ELLIPSIS
5.773502691896258...
>>> standard_deviation([6, 6, 8, 8])
1.1547005383792515
>>> standard_deviation([0, 0, 14, 14], sample=False)
7.0
>>> standard_deviation([0, 6, 8, 14], sample=False)
5.0
>>> standard_deviation([6, 6, 8, 8], sample=False)
1.0
(The results reported in Wikipedia are those expected for whole
population statistics and therefore are equal to the ones we get
by setting sample=False in the later tests.)
# Fictitious average monthly temperatures in Southern California.
# Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
>>> standard_deviation([70, 70, 70, 75, 80, 85, 90, 95, 90, 80, 75, 70])
9.003366373785...
>>> standard_deviation([70, 70, 70, 75, 80, 85, 90, 95, 90, 80, 75, 70], sample=False)
8.620067027323...
# Fictitious average monthly temperatures in Montana.
# Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
>>> standard_deviation([-32, -10, 20, 30, 60, 90, 100, 80, 60, 30, 10, -32])
45.1378360405574...
>>> standard_deviation([-32, -10, 20, 30, 60, 90, 100, 80, 60, 30, 10, -32], sample=False)
43.2161878106906...
webhelpers.number.Stats¶A container for data and statistics.
This class extends SimpleStats by calculating additional statistics,
and by storing all data seen. All values must be numeric (int,
long, and/or float), and you must call .finish() to generate
the additional statistics. That’s because the statistics here cannot be
calculated incrementally, but only after all data is known.
>>> stats = Stats()
>>> stats.extend([5, 10, 10])
>>> stats.count
3
>>> stats.finish()
>>> stats.mean # doctest: +ELLIPSIS
8.33333333333333...
>>> stats.median
10
>>> stats.standard_deviation
2.8867513459481287
All data is stored in a list and a set for later use:
>>> stats.list
[5, 10, 10]
>> stats.set
set([5, 10])
(The double prompt “>>” is used to hide the example from doctest.)
The stat attributes are None until you call .finish(). It’s
permissible – though not recommended – to add data after calling
.finish() and then call .finish() again. This recalculates the
stats over the entire data set.
In addition to the hook methods provided by SimpleStats, subclasses
can override ._finish-stats to provide additional statistics.
webhelpers.number.SimpleStats(numeric=False)¶Calculate a few simple statistics on data.
This class calculates the minimum, maximum, and count of all the values given to it. The values are not saved in the object. Usage:
>>> stats = SimpleStats()
>>> stats(2) # Add one data value.
>>> stats.extend([6, 4]) # Add several data values at once.
The statistics are available as instance attributes:
>>> stats.count
3
>>> stats.min
2
>>> stats.max
6
Non-numeric data is also allowed:
>>> stats2 = SimpleStats()
>>> stats2("foo")
>>> stats2("bar")
>>> stats2.count
2
>>> stats2.min
'bar'
>>> stats2.max
'foo'
.min and .max are None until the first data value is
registered.
Subclasses can override ._init_stats and ._update_stats to add
additional statistics.
The constructor accepts one optional argument, numeric. If true, the
instance accepts only values that are int, long, or float.
The default is false, which accepts any value. This is meant for instances
or subclasses that don’t want non-numeric values.
Helpers that are neither text, numeric, container, or date.
webhelpers.misc.all(seq, pred=None)¶Is pred(elm) true for all elements?
With the default predicate, this is the same as Python 2.5’s all()
function; i.e., it returns true if all elements are true.
>>> all(["A", "B"])
True
>>> all(["A", ""])
False
>>> all(["", ""])
False
>>> all(["A", "B", "C"], lambda x: x <= "C")
True
>>> all(["A", "B", "C"], lambda x: x < "C")
False
From recipe in itertools docs.
webhelpers.misc.any(seq, pred=None)¶Is pred(elm) is true for any element?
With the default predicate, this is the same as Python 2.5’s any()
function; i.e., it returns true if any element is true.
>>> any(["A", "B"])
True
>>> any(["A", ""])
True
>>> any(["", ""])
False
>>> any(["A", "B", "C"], lambda x: x <= "C")
True
>>> any(["A", "B", "C"], lambda x: x < "C")
True
From recipe in itertools docs.
webhelpers.misc.no(seq, pred=None)¶Is pred(elm) false for all elements?
With the default predicate, this returns true if all elements are false.
>>> no(["A", "B"])
False
>>> no(["A", ""])
False
>>> no(["", ""])
True
>>> no(["A", "B", "C"], lambda x: x <= "C")
False
>>> no(["X", "Y", "Z"], lambda x: x <="C")
True
From recipe in itertools docs.
webhelpers.misc.count_true(seq, pred=<function <lambda>>)¶How many elements is pred(elm) true for?
With the default predicate, this counts the number of true elements.
>>> count_true([1, 2, 0, "A", ""])
3
>>> count_true([1, "A", 2], lambda x: isinstance(x, int))
2
This is equivalent to the itertools.quantify recipe, which I couldn’t
get to work.
webhelpers.misc.convert_or_none(value, type_)¶Return the value converted to the type, or None if error.
type_ may be a Python type or any function taking one argument.
>>> print convert_or_none("5", int)
5
>>> print convert_or_none("A", int)
None
webhelpers.pylonslib.Flash(session_key='flash', categories=None, default_category=None)¶Accumulate a list of messages to show at the next page request.
__init__(session_key='flash', categories=None, default_category=None)¶Instantiate a Flash object.
session_key is the key to save the messages under in the user’s
session.
categories is an optional list which overrides the default list
of categories.
default_category overrides the default category used for messages
when none is specified.
__call__(message, category=None, ignore_duplicate=False)¶Add a message to the session.
message is the message text.
category is the message’s category. If not specified, the default
category will be used. Raise ValueError if the category is not
in the list of allowed categories.
If ignore_duplicate is true, don’t add the message if another
message with identical text has already been added. If the new
message has a different category than the original message, change the
original message to the new category.
pop_messages()¶Return all accumulated messages and delete them from the session.
The return value is a list of Message objects.
Functions that output text (not HTML).
Helpers for filtering, formatting, and transforming strings.
webhelpers.text.chop_at(s, sub, inclusive=False)¶Truncate string s at the first occurrence of sub.
If inclusive is true, truncate just after sub rather than at it.
>>> chop_at("plutocratic brats", "rat")
'plutoc'
>>> chop_at("plutocratic brats", "rat", True)
'plutocrat'
webhelpers.text.excerpt(text, phrase, radius=100, excerpt_string='...')¶Extract an excerpt from the text, or ‘’ if the phrase isn’t
found.
phrasetextradiusexcerpt_stringExample:
>>> excerpt("hello my world", "my", 3)
'...lo my wo...'
webhelpers.text.lchop(s, sub)¶Chop sub off the front of s if present.
>>> lchop("##This is a comment.##", "##")
'This is a comment.##'
The difference between lchop and s.lstrip is that lchop strips
only the exact prefix, while s.lstrip treats the argument as a set of
leading characters to delete regardless of order.
webhelpers.text.plural(n, singular, plural, with_number=True)¶Return the singular or plural form of a word, according to the number.
If with_number is true (default), the return value will be the number
followed by the word. Otherwise the word alone will be returned.
Usage:
>>> plural(2, "ox", "oxen")
'2 oxen'
>>> plural(2, "ox", "oxen", False)
'oxen'
webhelpers.text.rchop(s, sub)¶Chop sub off the end of s if present.
>>> rchop("##This is a comment.##", "##")
'##This is a comment.'
The difference between rchop and s.rstrip is that rchop strips
only the exact suffix, while s.rstrip treats the argument as a set of
trailing characters to delete regardless of order.
webhelpers.text.strip_leading_whitespace(s)¶Strip the leading whitespace in all lines in s.
This deletes all leading whitespace. textwrap.dedent deletes only
the whitespace common to all lines.
webhelpers.text.truncate(text, length=30, indicator='...', whole_word=False)¶Truncate text with replacement characters.
lengthtext before replacementindicatortext exceeds the length, this string will replace
the end of the stringwhole_wordExample:
>>> truncate('Once upon a time in a world far far away', 14)
'Once upon a...'
webhelpers.text.wrap_paragraphs(text, width=72)¶Wrap all paragraphs in a text string to the specified width.
width may be an int or a textwrap.TextWrapper instance.
The latter allows you to set other options besides the width, and is more
efficient when wrapping many texts.