Week scales, if enabled, by default shows the week number in range 1 to 53 (as defined by ISO-8601, see the reference section).
It might be worth pointing out here that the week number calculation is carried out within JpGraph and does not rely on the underlying OS date libraries. This makes the behavior consistent over several OS:s (at least M$ Windows does not comply to ISO-8601 or supply any way of doing this through the normal libraries, e.g. strftime())
You may modify the week behavior in three ways. You can specify (with SetStyle()) a different date format using the constants
Show week number To further modify the formatting of the actual week number you can optionally supply a format string with a call to
The format of the string should be a standard sprintf() syntax expecting an integer (the week number). By default a 'W' is prefixed to the number.
Show date of first day in week.
Show date of first day in week and short month
Show weeknumber of first day in week.
Show weeknumber of first day in week and month