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Last modified: 26 October 2016

URL: http://cxc.harvard.edu/chips/bugs/axes.html

Bugs: axes


Table of Contents

Bugs


Bugs

Undoing a set_axis call may not work correctly when used on an axis that is drawn with a logarithmic scale

The bug depends on what attributes are changed.

chips-1> x = 10**np.linspace(-1,1,20)
chips-2> y = x**2
chips-3> add_curve(x, y)
chips-4> get_plot_range()
         [-0.395, 10.495, -4.9895000000000005, 104.9995]
chips-5> log_scale(X_AXIS)
chips-6> get_plot_range()
         [0.07943282347242815, 12.589254117941673, -4.9895000000000005, 104.9995]
chips-7> set_axis(["pad", 0])
chips-8> get_plot_range()
         [0.1, 10.0, 0.010000000000000002, 100.0]
chips-9> undo()
chips-10> get_plot_range()
          [0.1, 10.0, 0.010000000000000002, 100.0]

The plot and ranges have not been reverted to the state at line chips-6. Calling log_scale on the axis again fixes up the plot:

chips-11> log_scale(X_AXIS)
chips-12> get_plot_range()
          [0.07943282347242815, 12.589254117941673, -4.9895000000000005, 104.9995]

Axes do not wrap around 360 degrees when using RA/Dec coordinates.

As a result, plotted contours or image may appear incorrect, and adjusting limits may not work correctly.

Setting the axis label

If the an axis label is set using the axis.x.label or axis.y.label attributes of an add_<object> call then the string must be surrounded by double quotes if it contains spaces; for example:

chips> add_curve(time, zoff, ['axis.y.label', '"Z offset (arcsec)"'])

Sexagesimal formats may produce invalid axis labels when the range is small

Axis labels displayed in sexagesimal format - e.g. tickformat=%ra - may be invalid when the axis range is small (several arcseconds) and a WCS transform is not attached to the axes.

This only affects plots with linear axes. It does not occur if the plot was created by either add_image or add_contour, or a WCS transform object was used when calling add_axis.

Only tangent-plane projections are supported

ChIPS will not display an image or contour with a WCS projection if it contains an unsupported axis transformation (e.g. RA--SIN,DEC--SIN). A warning, such as

chips WARNING: Unable to use world transform - RA---SIN, DEC--SIN is an unsupported type. Using physical transform.

is produced and the physical (or logical) system will be used instead.


Last modified: 26 October 2016
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