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4 Unit of length and the coordinate System

In PyChart, the X axis grows to the right, and the Y axis grows up (the same as PostScript, but different from X and Windows).

The length is measured in ``PostScript points'', which coincides with TeX points. Usually, one point is equal to 1/72 inch. Several variables and functions are provided to manipulate lengths.

Chart magnification can be changed by setting variable `theme.scale_factor`. One can convert a sample data value to a canval coordinate by calling two methods, `x_pos` and `y_pos` in `area.T` object.

See Also:

See Section 13.1 for the `theme` module.

See Section 6 for the `area` mobule.