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This command applies to timeseries where data are composed of dates/times. It has no meaning unless the command set xdata time is given also.


     set timefmt "<format string>"
     show timefmt

The string argument tells gnuplot how to read timedata from the datafile. The valid formats are:

Time Series timedata Format Specifiers
Format Explanation
%d day of the month, 1-31
%m month of the year, 1-12
%y year, 0-99
%Y year, 4-digit
%j day of the year, 1-365
%H hour, 0-24
%M minute, 0-60
%s seconds since the Unix epoch (1970-01-01 00:00 UTC)
%S second, 0-60
%b three-character abbreviation of the name of the month
%B name of the month
Any character is allowed in the string, but must match exactly. 3#3t (tab) is recognized. Backslash-octals (3#3nnn) are converted to char. If there is no separating character between the time/date elements, then %d, %m, %y, %H, %M and %S read two digits each, %Y reads four digits and %j reads three digits. %b requires three characters, and %B requires as many as it needs.

Spaces are treated slightly differently. A space in the string stands for zero or more whitespace characters in the file. That is, "%H %M" can be used to read "1220" and "12 20" as well as "12 20".

Each set of non-blank characters in the timedata counts as one column in the using n:n specification. Thus 11:11 25/12/76 21.0 consists of three columns. To avoid confusion, gnuplot requires that you provide a complete using specification if your file contains timedata.

Since gnuplot cannot read non-numerical text, if the date format includes the day or month in words, the format string must exclude this text. But it can still be printed with the "%a", "%A", "%b", or "%B" specifier: see set format (p. [*]) for more details about these and other options for printing timedata. (gnuplot will determine the proper month and weekday from the numerical values.)

See also set xdata (p. [*]) and Time/date (p. [*]) for more information.


     set timefmt "%d/%m/%Y\t%H:%M"

tells gnuplot to read date and time separated by tab. (But look closely at your data -- what began as a tab may have been converted to spaces somewhere along the line; the format string must match what is actually in the file.) See also data demo.

next up previous contents index
Next: Title Up: Set-show Previous: Timestamp   Contents   Index
Ethan Merritt 2007-03-03