How to migrate from plotpy V1¶
This section describes the steps to migrate python code using plotpy V1 to plotpy V2.
Updating the imports¶
PlotPy V1 to PlotPy V2¶
The following table gives the equivalence between plotpy V1 and plotpy V2 imports or objects.
For most of them, the change in the module path is the only difference (only the import statement have to be updated in your client code). For others, the third column of this table gives more details about the changes that may be required in your code.
plotpy v1 |
plotpy v2 |
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removed |
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removed |
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removed |
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removed |
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removed |
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removed |
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removed |
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removed |
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removed |
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removed |
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removed |
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removed |
PlotPy V1 to guidata V3¶
With the release of PlotPy V2, the DataSet related features have been moved
to the guidata package (from where they were originally extracted).
The following table gives the equivalence between PlotPy V1 and guidata V3 imports or objects.
plotpy v1 |
guidata v3 |
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removed |
New method for thresholding image item LUTs¶
The method plotpy.items.BaseImageItem.set_lut_threshold() has been
added. It allows to set the percentage of outliers to be clipped from the image
histogram values.
This method is available for all image items:
New options added to plot builder¶
The PlotItemBuilder factory class has been renamed to PlotBuilder,
because it provides not only methods for creating plot items, but also methods
for creating ready-to-use plots.
New methods for creating ready-to-use plots have been added to the class:
The method PlotBuilder.contours() has been added, in order to create
contour curves. It returns a list of plotpy.items.ContourItem objects.
See demo script tests/items/test_contour.py.
The new keyword parameter alpha_function has been added to the methods
PlotBuilder.image(), PlotBuilder.xyimage(),
PlotBuilder.maskedimage(), PlotBuilder.maskedxyimage(),
PlotBuilder.trimage(), PlotBuilder.rgbimage(), and
PlotBuilder.quadgrid(). It allows to specify a function to
compute the alpha channel of the image from the data values. The supported
functions are:
plotpy.constants.LUTAlpha.NONE(default)
Warning
The alpha_mask parameter has been removed from the methods
PlotBuilder.image(), PlotBuilder.xyimage(),
PlotBuilder.maskedimage(), PlotBuilder.maskedxyimage(),
PlotBuilder.trimage(), PlotBuilder.rgbimage(), and
PlotBuilder.quadgrid(). If you were using it, you should
replace it by the new alpha_function parameter.
Plot item icon handling¶
The guiqwt library was allowing to instantiate plot items without needing to create a QApplication instance (no GUI event loop was required). This was not the case with plotpy V1, so that it was not possible -for example- to serialize/deserialize plot items to JSON without creating a QApplication instance.
With plotpy V2, this has been fixed by removing the QIcon instantiation from the plot items constructors (call to QwtPlotItem.setIcon method).
Note that -in the meantime- QwtPlotItem.setIcon and QwtPlotItem.icon methods have also been removed in PythonQwt V0.14.3.
Code relying on this feature should thus be updated to use the new get_icon_name method instead, i.e. get_icon(item.get_icon_name()) instead of item.icon().
