8.2. "calendar" — General calendar-related functions
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**Source code:** Lib/calendar.py

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This module allows you to output calendars like the Unix **cal**
program, and provides additional useful functions related to the
calendar. By default, these calendars have Monday as the first day of
the week, and Sunday as the last (the European convention). Use
"setfirstweekday()" to set the first day of the week to Sunday (6) or
to any other weekday.  Parameters that specify dates are given as
integers. For related functionality, see also the "datetime" and
"time" modules.

Most of these functions and classes rely on the "datetime" module
which uses an idealized calendar, the current Gregorian calendar
indefinitely extended in both directions.  This matches the definition
of the “proleptic Gregorian” calendar in Dershowitz and Reingold’s
book “Calendrical Calculations”, where it’s the base calendar for all
computations.

class calendar.Calendar([firstweekday])

   Creates a "Calendar" object. *firstweekday* is an integer
   specifying the first day of the week. "0" is Monday (the default),
   "6" is Sunday.

   A "Calendar" object provides several methods that can be used for
   preparing the calendar data for formatting. This class doesn’t do
   any formatting itself. This is the job of subclasses.

   New in version 2.5.

   "Calendar" instances have the following methods:

   iterweekdays()

      Return an iterator for the week day numbers that will be used
      for one week.  The first value from the iterator will be the
      same as the value of the "firstweekday" property.

   itermonthdates(year, month)

      Return an iterator for the month *month* (1–12) in the year
      *year*. This iterator will return all days (as "datetime.date"
      objects) for the month and all days before the start of the
      month or after the end of the month that are required to get a
      complete week.

   itermonthdays2(year, month)

      Return an iterator for the month *month* in the year *year*
      similar to "itermonthdates()". Days returned will be tuples
      consisting of a day number and a week day number.

   itermonthdays(year, month)

      Return an iterator for the month *month* in the year *year*
      similar to "itermonthdates()". Days returned will simply be day
      numbers.

   monthdatescalendar(year, month)

      Return a list of the weeks in the month *month* of the *year* as
      full weeks.  Weeks are lists of seven "datetime.date" objects.

   monthdays2calendar(year, month)

      Return a list of the weeks in the month *month* of the *year* as
      full weeks.  Weeks are lists of seven tuples of day numbers and
      weekday numbers.

   monthdayscalendar(year, month)

      Return a list of the weeks in the month *month* of the *year* as
      full weeks.  Weeks are lists of seven day numbers.

   yeardatescalendar(year[, width])

      Return the data for the specified year ready for formatting. The
      return value is a list of month rows. Each month row contains up
      to *width* months (defaulting to 3). Each month contains between
      4 and 6 weeks and each week contains 1–7 days. Days are
      "datetime.date" objects.

   yeardays2calendar(year[, width])

      Return the data for the specified year ready for formatting
      (similar to "yeardatescalendar()"). Entries in the week lists
      are tuples of day numbers and weekday numbers. Day numbers
      outside this month are zero.

   yeardayscalendar(year[, width])

      Return the data for the specified year ready for formatting
      (similar to "yeardatescalendar()"). Entries in the week lists
      are day numbers. Day numbers outside this month are zero.

class calendar.TextCalendar([firstweekday])

   This class can be used to generate plain text calendars.

   New in version 2.5.

   "TextCalendar" instances have the following methods:

   formatmonth(theyear, themonth[, w[, l]])

      Return a month’s calendar in a multi-line string. If *w* is
      provided, it specifies the width of the date columns, which are
      centered. If *l* is given, it specifies the number of lines that
      each week will use. Depends on the first weekday as specified in
      the constructor or set by the "setfirstweekday()" method.

   prmonth(theyear, themonth[, w[, l]])

      Print a month’s calendar as returned by "formatmonth()".

   formatyear(theyear[, w[, l[, c[, m]]]])

      Return a *m*-column calendar for an entire year as a multi-line
      string. Optional parameters *w*, *l*, and *c* are for date
      column width, lines per week, and number of spaces between month
      columns, respectively. Depends on the first weekday as specified
      in the constructor or set by the "setfirstweekday()" method.
      The earliest year for which a calendar can be generated is
      platform-dependent.

   pryear(theyear[, w[, l[, c[, m]]]])

      Print the calendar for an entire year as returned by
      "formatyear()".

class calendar.HTMLCalendar([firstweekday])

   This class can be used to generate HTML calendars.

   New in version 2.5.

   "HTMLCalendar" instances have the following methods:

   formatmonth(theyear, themonth[, withyear])

      Return a month’s calendar as an HTML table. If *withyear* is
      true the year will be included in the header, otherwise just the
      month name will be used.

   formatyear(theyear[, width])

      Return a year’s calendar as an HTML table. *width* (defaulting
      to 3) specifies the number of months per row.

   formatyearpage(theyear[, width[, css[, encoding]]])

      Return a year’s calendar as a complete HTML page. *width*
      (defaulting to 3) specifies the number of months per row. *css*
      is the name for the cascading style sheet to be used. "None" can
      be passed if no style sheet should be used. *encoding* specifies
      the encoding to be used for the output (defaulting to the system
      default encoding).

class calendar.LocaleTextCalendar([firstweekday[, locale]])

   This subclass of "TextCalendar" can be passed a locale name in the
   constructor and will return month and weekday names in the
   specified locale. If this locale includes an encoding all strings
   containing month and weekday names will be returned as unicode.

   New in version 2.5.

class calendar.LocaleHTMLCalendar([firstweekday[, locale]])

   This subclass of "HTMLCalendar" can be passed a locale name in the
   constructor and will return month and weekday names in the
   specified locale. If this locale includes an encoding all strings
   containing month and weekday names will be returned as unicode.

   New in version 2.5.

Note: The "formatweekday()" and "formatmonthname()" methods of these
  two classes temporarily change the current locale to the given
  *locale*. Because the current locale is a process-wide setting, they
  are not thread-safe.

For simple text calendars this module provides the following
functions.

calendar.setfirstweekday(weekday)

   Sets the weekday ("0" is Monday, "6" is Sunday) to start each week.
   The values "MONDAY", "TUESDAY", "WEDNESDAY", "THURSDAY", "FRIDAY",
   "SATURDAY", and "SUNDAY" are provided for convenience. For example,
   to set the first weekday to Sunday:

      import calendar
      calendar.setfirstweekday(calendar.SUNDAY)

   New in version 2.0.

calendar.firstweekday()

   Returns the current setting for the weekday to start each week.

   New in version 2.0.

calendar.isleap(year)

   Returns "True" if *year* is a leap year, otherwise "False".

calendar.leapdays(y1, y2)

   Returns the number of leap years in the range from *y1* to *y2*
   (exclusive), where *y1* and *y2* are years.

   Changed in version 2.0: This function didn’t work for ranges
   spanning a century change in Python 1.5.2.

calendar.weekday(year, month, day)

   Returns the day of the week ("0" is Monday) for *year* ("1970"–…),
   *month* ("1"–"12"), *day* ("1"–"31").

calendar.weekheader(n)

   Return a header containing abbreviated weekday names. *n* specifies
   the width in characters for one weekday.

calendar.monthrange(year, month)

   Returns weekday of first day of the month and number of days in
   month,  for the specified *year* and *month*.

calendar.monthcalendar(year, month)

   Returns a matrix representing a month’s calendar.  Each row
   represents a week; days outside of the month a represented by
   zeros. Each week begins with Monday unless set by
   "setfirstweekday()".

calendar.prmonth(theyear, themonth[, w[, l]])

   Prints a month’s calendar as returned by "month()".

calendar.month(theyear, themonth[, w[, l]])

   Returns a month’s calendar in a multi-line string using the
   "formatmonth()" of the "TextCalendar" class.

   New in version 2.0.

calendar.prcal(year[, w[, l[c]]])

   Prints the calendar for an entire year as returned by
   "calendar()".

calendar.calendar(year[, w[, l[c]]])

   Returns a 3-column calendar for an entire year as a multi-line
   string using the "formatyear()" of the "TextCalendar" class.

   New in version 2.0.

calendar.timegm(tuple)

   An unrelated but handy function that takes a time tuple such as
   returned by the "gmtime()" function in the "time" module, and
   returns the corresponding Unix timestamp value, assuming an epoch
   of 1970, and the POSIX encoding.  In fact, "time.gmtime()" and
   "timegm()" are each others’ inverse.

   New in version 2.0.

The "calendar" module exports the following data attributes:

calendar.day_name

   An array that represents the days of the week in the current
   locale.

calendar.day_abbr

   An array that represents the abbreviated days of the week in the
   current locale.

calendar.month_name

   An array that represents the months of the year in the current
   locale.  This follows normal convention of January being month
   number 1, so it has a length of 13 and  "month_name[0]" is the
   empty string.

calendar.month_abbr

   An array that represents the abbreviated months of the year in the
   current locale.  This follows normal convention of January being
   month number 1, so it has a length of 13 and  "month_abbr[0]" is
   the empty string.

See also:

  Module "datetime"
     Object-oriented interface to dates and times with similar
     functionality to the "time" module.

  Module "time"
     Low-level time related functions.
