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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).
Lengths are measured by "Postscript points", which coincides with TeX points. One point is equal to 1/72 inch. Several variables and functions are provided to manipulate lengths:
theme.scale_factor | Variable |
Defines chart magnification. The default value is 1.0, meaning that one point actually means one Postscript point. Setting this value to 3.0, for example, makes PyChart draw everything three times larger. |
area.x_pos XVAL | Function |
Converts X XVAL to a coordinate on the canvas (see canvas). |
area.y_pos YVAL | Function |
Converts Y YVAL to a coordinate on the canvas (see canvas). |
ar = area.T(loc=(50, 50), size=(100, 100), xrange=(0,200), yrange=(0, 1000)) px = ar.x_pos(50) py = ar.y_pos(100)
In the above example, the chart is drawn on the area defined by
rectangle (50, 50) - (150, 150). The point (px, py
) will
be at (75, 60), which is the screen location at which the point
(50, 100) would be drawn (i.e., 50 + 100 * 50/200 = 75,
50 + 100 * 100 / 1000 = 60).