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13.3 Changing the default behavior via environment variable PYCHART_OPTIONS

The variables in the `theme` module can also be set via environment variable `PYCHART_OPTIONS`. The value of this variable, if set, should be a sequence of `var=val`, separated by space. For instance, the below example tells PyChart to write to file foo.pdf and use Times-Roman as the default font.

    % PYCHART_OPTIONS="output=foo.pdf font-family=Times"
    % export PYCHART_OPTIONS

The summary of attributes that can be set via `PYCHART_OPTIONS` follows.

font-family=name:
  family Same as setting `theme.default_font_family` variable.

font-size=size:
  size Same as setting `theme.default_font_size` variable.

line-width=points:
  Same as setting `theme.default_line_width` variable.

scale=n:
  Same as setting `theme.scale_factor` variable.

color=[yes|no]:
  Same as setting `theme.use_color` variable.

debug-level=N:
  Same as setting `theme.debug_level` variable.

bbox=LEFT,BOTTOM,RIGHT,TOP:
  This option sets `theme.bounding_box` and/or `theme.delta_bounding_box`. The value of this option is a sequence of four values, separated by commas. Each value is of the form, `+`num, `-`num, or num. `+`num and `-`num adds to or subtracts from the bounding-box value computed by PyChart (the unit is PostScript points; See Section 4.) num sets the bounding box at that value. For example,

      bbox=-10,0,+10,100

  Extends the bounding box 10 points to both left and right, and sets the vertical stretch from 0 to 100.