fix magnitude of limits in case of a single value

[sergey-yaroslavtsev]

a strange bug appears in module because it uses matplotlib==3.11.0

minimal reproduction of an issue:

import matplotlib
matplotlib.use("Agg")
import matplotlib.pyplot as plt

V = 207769447.39       
DELTA = 0.044             
fig, ax = plt.subplots(figsize=(7.4, 4.9), dpi=100)
# thin view at large magnitude, (llike PyMca.setLimits)
ax.set_xlim(-DELTA, DELTA)
ax.set_ylim(V - DELTA, V + DELTA)
# text outside that thin view
ax.text(0.0, 0.0, "marker", transform=ax.transData)
fig.canvas.draw()          # crashes on >= 3.11, fine on <= 3.10

tested on 3.10, 3.11.0, 3.11.1

[woutdenolf]

This might be the proper fix:

@@ -2098,11 +2098,11 @@ def insertYMarker(self, y, legend=None, text=None,
             xmin, xmax = self.getGraphXLimits()
             delta = abs(xmax - xmin)
             if xmin > xmax:
                 xmax = xmin
             xmax -= 0.005 * delta
-            line._infoText = self.ax.text(y, xmax, text,
+            line._infoText = self.ax.text(xmax, y, text,
                                           color=color,
                                           horizontalalignment='left',
                                           verticalalignment='top')
         line._plot_options = ["ymarker"]
         if selectable:

[woutdenolf]

MRE to reproduce the bug with PyMca's MatplotlibBackend

from PyMca5.PyMcaGraph.backends.MatplotlibBackend import MatplotlibBackend

V = 1e10

backend = MatplotlibBackend()
backend.setLimits(0, 1024, V, V)
backend.insertYMarker(V, text="marker")
backend.ax.get_figure().canvas.draw()
print("OK")

The fix in #1233 (comment) solves it.

[sergey-yaroslavtsev]

I have data which is 1x1000x1000 -> ROI image -> select "1D data is first dimension"
Old behavior -> error; your fix give same error; fix in PR works.

It a strange thing to do... but user found it

[sergey-yaroslavtsev]

The full error message:

Error

Traceback (most recent call last):
  File "<string>", line 1244, in __roiImaging
  File "C:\Users\yaroslav\PycharmProjects\PyMca\pymca\src\PyMca5\PyMcaGui\pymca\QStackWidget.py", line 637, in loadStack
    self.setStack(stack)
  File "C:\Users\yaroslav\PycharmProjects\PyMca\pymca\src\PyMca5\PyMcaGui\pymca\QStackWidget.py", line 255, in setStack
    StackBase.StackBase.setStack(self, *var, **kw)
  File "C:\Users\yaroslav\PycharmProjects\PyMca\pymca\src\PyMca5\PyMcaCore\StackBase.py", line 247, in setStack
    self.stackUpdated(info.get("positioners", None))
  File "C:\Users\yaroslav\PycharmProjects\PyMca\pymca\src\PyMca5\PyMcaCore\StackBase.py", line 370, in stackUpdated
    self.showOriginalMca()
  File "C:\Users\yaroslav\PycharmProjects\PyMca\pymca\src\PyMca5\PyMcaGui\pymca\QStackWidget.py", line 1033, in showOriginalMca
    self.sendMcaSelection(self._mcaData0, action="ADD")
  File "C:\Users\yaroslav\PycharmProjects\PyMca\pymca\src\PyMca5\PyMcaGui\pymca\QStackWidget.py", line 1217, in sendMcaSelection
    self.mcaWidget._addSelection([sel])
  File "C:\Users\yaroslav\PycharmProjects\PyMca\pymca\src\PyMca5\PyMcaGui\pymca\McaWindow.py", line 1088, in _addSelection
    self.addCurve(xhelp, data,
  File "C:\Users\yaroslav\PycharmProjects\PyMca\pymca\src\PyMca5\PyMcaGui\pymca\McaWindow.py", line 1594, in addCurve
    super(McaWindow, self).addCurve(x, y, legend=legend, info=info,
  File "C:\Users\yaroslav\PycharmProjects\PyMca\pymca\src\PyMca5\PyMcaGui\pymca\ScanWindow.py", line 1313, in addCurve
    super(ScanWindow, self).addCurve(x, y, legend=legend, info=info,
  File "C:\Users\yaroslav\PycharmProjects\PyMca\pymca\src\PyMca5\PyMcaGraph\Plot.py", line 546, in addCurve
    self.resetZoom()
  File "C:\Users\yaroslav\PycharmProjects\PyMca\pymca\src\PyMca5\PyMcaGui\plotting\PlotWindow.py", line 596, in resetZoom
    super(PlotWindow, self).resetZoom(**kw)
  File "C:\Users\yaroslav\PycharmProjects\PyMca\pymca\src\PyMca5\PyMcaGraph\Plot.py", line 1099, in resetZoom
    self._plot.resetZoom(dataMargins)
  File "C:\Users\yaroslav\PycharmProjects\PyMca\pymca\src\PyMca5\PyMcaGraph\backends\MatplotlibBackend.py", line 2203, in resetZoom
    self.replot()
  File "C:\Users\yaroslav\PycharmProjects\PyMca\pymca\src\PyMca5\PyMcaGraph\backends\MatplotlibBackend.py", line 2219, in replot
    self.graph.draw()
  File "C:\Users\yaroslav\PycharmProjects\PyMca\.venv\Lib\site-packages\matplotlib\backends\backend_agg.py", line 438, in draw
    self.figure.draw(self.renderer)
  File "C:\Users\yaroslav\PycharmProjects\PyMca\.venv\Lib\site-packages\matplotlib\artist.py", line 94, in draw_wrapper
    result = draw(artist, renderer, *args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\yaroslav\PycharmProjects\PyMca\.venv\Lib\site-packages\matplotlib\artist.py", line 71, in draw_wrapper
    return draw(artist, renderer)
           ^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\yaroslav\PycharmProjects\PyMca\.venv\Lib\site-packages\matplotlib\figure.py", line 3282, in draw
    mimage._draw_list_compositing_images(
  File "C:\Users\yaroslav\PycharmProjects\PyMca\.venv\Lib\site-packages\matplotlib\image.py", line 133, in _draw_list_compositing_images
    a.draw(renderer)
  File "C:\Users\yaroslav\PycharmProjects\PyMca\.venv\Lib\site-packages\matplotlib\artist.py", line 71, in draw_wrapper
    return draw(artist, renderer)
           ^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\yaroslav\PycharmProjects\PyMca\.venv\Lib\site-packages\matplotlib\axes\_base.py", line 3367, in draw
    mimage._draw_list_compositing_images(
  File "C:\Users\yaroslav\PycharmProjects\PyMca\.venv\Lib\site-packages\matplotlib\image.py", line 133, in _draw_list_compositing_images
    a.draw(renderer)
  File "C:\Users\yaroslav\PycharmProjects\PyMca\.venv\Lib\site-packages\matplotlib\artist.py", line 71, in draw_wrapper
    return draw(artist, renderer)
           ^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\yaroslav\PycharmProjects\PyMca\.venv\Lib\site-packages\matplotlib\text.py", line 909, in draw
    textrenderer.draw_text(gc, x, y, clean_line,
  File "C:\Users\yaroslav\PycharmProjects\PyMca\.venv\Lib\site-packages\matplotlib\backends\backend_agg.py", line 245, in draw_text
    self._draw_text_glyphs_and_boxes(
  File "C:\Users\yaroslav\PycharmProjects\PyMca\.venv\Lib\site-packages\matplotlib\backends\backend_agg.py", line 182, in _draw_text_glyphs_and_boxes
    font._set_transform(
TypeError: _set_transform(): incompatible function arguments. The following argument types are supported:
    1. (self: matplotlib.ft2font.FT2Font, matrix: typing.Annotated[collections.abc.Sequence[typing.Annotated[collections.abc.Sequence[typing.SupportsInt | typing.SupportsIndex], "FixedSize(2)"]], "FixedSize(2)"], delta: typing.Annotated[collections.abc.Sequence[typing.SupportsInt | typing.SupportsIndex], "FixedSize(2)"]) -> None

Invoked with: <matplotlib.ft2font.FT2Font object at 0x0000020E3EA31AF0>, array([[65536,     0],
       [    0, 65536]]), [42538, -54964436860202]

[woutdenolf]

Sorry I cannot reproduce

import sys
import h5py
import numpy as np

from PyQt5.QtWidgets import QApplication
from PyMca5.PyMcaGui.pymca.QStackWidget import QStackWidget
from PyMca5.PyMcaCore import StackBase
from PyMca5.PyMcaCore import DataObject

filename = "test_stack.h5"

with h5py.File(filename, "w") as f:
    f.create_dataset(
        "data",
        shape=(1, 1000, 1000),
        dtype=np.float32
    )

app = QApplication(sys.argv)

w = QStackWidget()
w.show()

stack = DataObject.DataObject()

with h5py.File(filename, "r") as f:
    stack.data = f["data"][()]

# "1D data is first dimension"
stack.info = {
    "McaIndex": 0,
    "SourceType": "HDF5"
}

w.setStack(stack)

sys.exit(app.exec())

The reason I'm insisting to understand what the problem is exactly is the magic abs(vmin) * 0.05. The function already is full of magic numbers like 0.044 and 0.005

[sergey-yaroslavtsev]

0.044 is "magic"number - historical for PyMca - the only reason i keep it is because it was working like this before. It probably can be substituted entirely with a new one.

abs(vmin) * 0.05 - is a new magic number - but it is only "half-magic" 😄 the main point of it is to have gaps in % and not in absolute values - this is exactly where new matplotlib fails (see example in PR comment).
We can change 5% to any other reasonable "magic"-number - this will not make a big difference.

part of the problem is that float32 (as example) keeps values in big range but with different sensitivity/resolution, so for values 2*10^8 (again example from actual bug) it could not see difference of 0.044 (initial magic value). That is why Limits should be set in % and not in absolute. Otherwise the behavior is unpredictable.

in particular it lead to overflow of pixel dimension (see the the end of original error) , which crush the positioning of the Marker (see the beginning of the original error - it happens on call of insertMarker).

So to reproduce the problem - (1) bad range + (2) use position.

try to set data like np.logspace(-9, 9, 1100 * 1100, dtype=np.float32)
and then place w.mcaWidget.insertMarker(0.0, 0.0, text="")

[woutdenolf]

Now I finally understand what the problem is

>>> numpy.float32(1e10) == (numpy.float32(1e10) + 0.044)
np.True_

This code tries to ensure that xmin != xmax.

Since this depends on the float-precision the delta must be relative not absolute.

We keep the magic 0.044 is a lower bound.

Ok I'm fine with this.