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BUG: PcolorImage handles non-contiguous arrays, provides data readout #6930

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Merged
merged 2 commits into from
Aug 25, 2016
Merged

BUG: PcolorImage handles non-contiguous arrays, provides data readout #6930

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ebfe81d
BUG: PcolorImage handles non-contiguous arrays, provides data readout
efiring Aug 9, 2016
f1b6135
DOC: add docstring for set_array; improve related docstrings in _axes.py
efiring Aug 24, 2016
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15 changes: 8 additions & 7 deletions lib/matplotlib/axes/_axes.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5522,8 +5522,9 @@ def pcolormesh(self, *args, **kwargs):
.. seealso::

:func:`~matplotlib.pyplot.pcolor`
For an explanation of the grid orientation and the
expansion of 1-D *X* and/or *Y* to 2-D arrays.
For an explanation of the grid orientation
(:ref:`Grid Orientation <axes-pcolor-grid-orientation>`)
and the expansion of 1-D *X* and/or *Y* to 2-D arrays.
"""
if not self._hold:
self.cla()
Expand Down Expand Up @@ -5637,10 +5638,10 @@ def pcolorfast(self, *args, **kwargs):
(*nr*-1, *nc*-1). All cells are rectangles of the same size.
This is the fastest version.

*x*, *y* are 1D arrays of length *nc* +1 and *nr* +1, respectively,
giving the x and y boundaries of the cells. Hence the cells are
rectangular but the grid may be nonuniform. The speed is
intermediate. (The grid is checked, and if found to be
*x*, *y* are monotonic 1D arrays of length *nc* +1 and *nr* +1,
respectively, giving the x and y boundaries of the cells. Hence
the cells are rectangular but the grid may be nonuniform. The
speed is intermediate. (The grid is checked, and if found to be
uniform the fast version is used.)

*X* and *Y* are 2D arrays with shape (*nr* +1, *nc* +1) that specify
Expand All @@ -5654,7 +5655,7 @@ def pcolorfast(self, *args, **kwargs):

Note that the column index corresponds to the x-coordinate,
and the row index corresponds to y; for details, see
the "Grid Orientation" section below.
:ref:`Grid Orientation <axes-pcolor-grid-orientation>`.

Optional keyword arguments:

Expand Down
39 changes: 37 additions & 2 deletions lib/matplotlib/image.py
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Original file line number Diff line number Diff line change
Expand Up @@ -839,8 +839,8 @@ def set_data(self, x, y, A):
"""
Set the grid for the pixel centers, and the pixel values.

*x* and *y* are 1-D ndarrays of lengths N and M, respectively,
specifying pixel centers
*x* and *y* are monotonic 1-D ndarrays of lengths N and M,
respectively, specifying pixel centers

*A* is an (M,N) ndarray or masked array of values to be
colormapped, or a (M,N,3) RGB array, or a (M,N,4) RGBA
Expand Down Expand Up @@ -959,6 +959,19 @@ def _check_unsampled_image(self, renderer):
return False

def set_data(self, x, y, A):
"""
Set the grid for the rectangle boundaries, and the data values.

*x* and *y* are monotonic 1-D ndarrays of lengths N+1 and M+1,
respectively, specifying rectangle boundaries. If None,
they will be created as uniform arrays from 0 through N
and 0 through M, respectively.

*A* is an (M,N) ndarray or masked array of values to be
colormapped, or a (M,N,3) RGB array, or a (M,N,4) RGBA
array.

"""
A = cbook.safe_masked_invalid(A, copy=True)
if x is None:
x = np.arange(0, A.shape[1]+1, dtype=np.float64)
Expand All @@ -985,6 +998,15 @@ def set_data(self, x, y, A):
self.is_grayscale = True
else:
raise ValueError("3D arrays must have RGB or RGBA as last dim")

# For efficient cursor readout, ensure x and y are increasing.
if x[-1] < x[0]:
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Do we enforce that x/y are monotonic someplace else?

If we bump the minimum numpy to 1.7, searchsorted takes in a sorter kwarg which is an array with the indexes in sorted order (https://docs.scipy.org/doc/numpy/reference/generated/numpy.searchsorted.html)

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No, we have never enforced monotonic x or y for any of the pcolor-like functions; that has implicitly been left to the user. If the user supplies non-monotonic x and/or y the plotted results will be odd, and with this PR as-is the cursor readout will sometimes be hard to predict--but the plot won't make sense anyway, so I don't see that it matters. So it seems to me that you are raising a question that is independent of this PR--should we add more input validation for this category of plot?

x = x[::-1]
A = A[:, ::-1]
if y[-1] < y[0]:
y = y[::-1]
A = A[::-1]

self._A = A
self._Ax = x
self._Ay = y
Expand All @@ -994,6 +1016,19 @@ def set_data(self, x, y, A):
def set_array(self, *args):
raise NotImplementedError('Method not supported')

def get_cursor_data(self, event):
"""Get the cursor data for a given event"""
x, y = event.xdata, event.ydata
if (x < self._Ax[0] or x > self._Ax[-1] or
y < self._Ay[0] or y > self._Ay[-1]):
return None
j = np.searchsorted(self._Ax, x) - 1
i = np.searchsorted(self._Ay, y) - 1
try:
return self._A[i, j]
except:
return None


class FigureImage(_ImageBase):
zorder = 0
Expand Down
4 changes: 2 additions & 2 deletions src/_image_wrapper.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -411,9 +411,9 @@ static PyObject *image_pcolor2(PyObject *self, PyObject *args, PyObject *kwds)

if (!PyArg_ParseTuple(args,
"O&O&O&II(ffff)O&:pcolor2",
&x.converter,
&x.converter_contiguous,
&x,
&y.converter,
&y.converter_contiguous,
&y,
&d.converter_contiguous,
&d,
Expand Down