matplotlib 3.5.1

NotesOther ParametersParametersReturnsBackRef
pcolormesh(self, *args, alpha=None, norm=None, cmap=None, vmin=None, vmax=None, shading=None, antialiased=False, data=None, **kwargs)

Call signature:

pcolormesh([X, Y,] C, **kwargs)

X and Y can be used to specify the corners of the quadrilaterals.

.. hint:: 
    `~.Axes.pcolormesh` is similar to `~.Axes.pcolor`. It is much faster
    and preferred in most cases. For a detailed discussion on the
    differences see :ref:`Differences between pcolor() and pcolormesh()
    <differences-pcolor-pcolormesh>`.

Notes

Masked arrays

C may be a masked array. If C[i, j] is masked, the corresponding quadrilateral will be transparent. Masking of X and Y is not supported. Use ~.Axes.pcolor if you need this functionality.

            <Unimplemented 'target' '.. _axes-pcolormesh-grid-orientation:'>
           

Grid orientation

The grid orientation follows the standard matrix convention: An array C with shape (nrows, ncolumns) is plotted with the column number as X and the row number as Y.

            <Unimplemented 'target' '.. _differences-pcolor-pcolormesh:'>
           

Differences between pcolor() and pcolormesh()

Both methods are used to create a pseudocolor plot of a 2D array using quadrilaterals.

The main difference lies in the created object and internal data handling: While ~.Axes.pcolor returns a .PolyCollection , ~.Axes.pcolormesh returns a .QuadMesh . The latter is more specialized for the given purpose and thus is faster. It should almost always be preferred.

There is also a slight difference in the handling of masked arrays. Both ~.Axes.pcolor and ~.Axes.pcolormesh support masked arrays for C. However, only ~.Axes.pcolor supports masked arrays for X and Y. The reason lies in the internal handling of the masked values. ~.Axes.pcolor leaves out the respective polygons from the PolyCollection. ~.Axes.pcolormesh sets the facecolor of the masked elements to transparent. You can see the difference when using edgecolors. While all edges are drawn irrespective of masking in a QuadMesh, the edge between two adjacent masked quadrilaterals in ~.Axes.pcolor is not drawn as the corresponding polygons do not exist in the PolyCollection.

Another difference is the support of Gouraud shading in ~.Axes.pcolormesh , which is not available with ~.Axes.pcolor .

Other Parameters

data : indexable object, optional

If given, all parameters also accept a string s , which is interpreted as data[s] (unless this raises an exception).

**kwargs :

Additionally, the following arguments are allowed. They are passed along to the ~matplotlib.collections.QuadMesh constructor:

Properties: :

agg_filter: a filter function, which takes a (m, n, 3) float array and a dpi value, and returns a (m, n, 3) array alpha: array-like or scalar or None animated: bool antialiased or aa or antialiaseds: bool or list of bools array: (M, N) array-like or M*N array-like capstyle: .CapStyle or {'butt', 'projecting', 'round'} clim: (vmin: float, vmax: float) clip_box: .Bbox clip_on: bool clip_path: Patch or (Path, Transform) or None cmap: .Colormap or str or None color: color or list of rgba tuples edgecolor or ec or edgecolors: color or list of colors or 'face' facecolor or facecolors or fc: color or list of colors figure: .Figure gid: str hatch: {'/', '\\', '|', '-', '+', 'x', 'o', 'O', '.', '*'} in_layout: bool joinstyle: .JoinStyle or {'miter', 'round', 'bevel'} label: object linestyle or dashes or linestyles or ls: str or tuple or list thereof linewidth or linewidths or lw: float or list of floats norm: .Normalize or None offset_transform: .Transform offsets: (N, 2) or (2,) array-like path_effects: .AbstractPathEffect picker: None or bool or float or callable pickradius: float rasterized: bool sketch_params: (scale: float, length: float, randomness: float) snap: bool or None transform: .Transform url: str urls: list of str or None visible: bool zorder: float

Parameters

C : 2D array-like

The color-mapped values.

X, Y : array-like, optional

The coordinates of the corners of quadrilaterals of a pcolormesh:

(X[i+1, j], Y[i+1, j])       (X[i+1, j+1], Y[i+1, j+1])
                      +-----+
                      |     |
                      +-----+
    (X[i, j], Y[i, j])       (X[i, j+1], Y[i, j+1])

Note that the column index corresponds to the x-coordinate, and the row index corresponds to y. For details, see the Notes <axes-pcolormesh-grid-orientation> section below.

If shading='flat' the dimensions of X and Y should be one greater than those of C, and the quadrilateral is colored due to the value at C[i, j] . If X, Y and C have equal dimensions, a warning will be raised and the last row and column of C will be ignored.

If shading='nearest' or 'gouraud' , the dimensions of X and Y should be the same as those of C (if not, a ValueError will be raised). For 'nearest' the color C[i, j] is centered on (X[i, j], Y[i, j]) . For 'gouraud' , a smooth interpolation is caried out between the quadrilateral corners.

If X and/or Y are 1-D arrays or column vectors they will be expanded as needed into the appropriate 2D arrays, making a rectangular grid.

cmap : str or `~matplotlib.colors.Colormap`, default: :rc:`image.cmap`

A Colormap instance or registered colormap name. The colormap maps the C values to colors.

norm : `~matplotlib.colors.Normalize`, optional

The Normalize instance scales the data values to the canonical colormap range [0, 1] for mapping to colors. By default, the data range is mapped to the colorbar range using linear scaling.

vmin, vmax : float, default: None

The colorbar range. If None, suitable min/max values are automatically chosen by the .Normalize instance (defaults to the respective min/max values of C in case of the default linear scaling). It is an error to use vmin/vmax when norm is given.

edgecolors : {'none', None, 'face', color, color sequence}, optional

The color of the edges. Defaults to 'none'. Possible values:

  • 'none' or '': No edge.

  • None: patch.edgecolor will be used. Note that currently patch.force_edgecolor has to be True for this to work.

  • 'face': Use the adjacent face color.

  • A color or sequence of colors will set the edge color.

The singular form edgecolor works as an alias.

alpha : float, default: None

The alpha blending value, between 0 (transparent) and 1 (opaque).

shading : {'flat', 'nearest', 'gouraud', 'auto'}, optional

The fill style for the quadrilateral; defaults to 'flat' or pcolor.shading . Possible values:

  • 'flat': A solid color is used for each quad. The color of the quad (i, j), (i+1, j), (i, j+1), (i+1, j+1) is given by C[i, j] . The dimensions of X and Y should be one greater than those of C; if they are the same as C, then a deprecation warning is raised, and the last row and column of C are dropped.

  • 'nearest': Each grid point will have a color centered on it, extending halfway between the adjacent grid centers. The dimensions of X and Y must be the same as C.

  • 'gouraud': Each quad will be Gouraud shaded: The color of the corners (i', j') are given by C[i', j'] . The color values of the area in between is interpolated from the corner values. The dimensions of X and Y must be the same as C. When Gouraud shading is used, edgecolors is ignored.

  • 'auto': Choose 'flat' if dimensions of X and Y are one larger than C. Choose 'nearest' if dimensions are the same.

See /gallery/images_contours_and_fields/pcolormesh_grids for more description.

snap : bool, default: False

Whether to snap the mesh to pixel boundaries.

rasterized : bool, optional

Rasterize the pcolormesh when drawing vector graphics. This can speed up rendering and produce smaller files for large data sets. See also /gallery/misc/rasterization_demo .

Returns

`matplotlib.collections.QuadMesh`

Create a pseudocolor plot with a non-regular rectangular grid.

See Also

imshow

If X and Y are each equidistant, :None:None:`~.Axes.imshow` can be a faster alternative.

pcolor

An alternative implementation with slightly different features. For a detailed discussion on the differences see :None:ref:`Differences between pcolor() and pcolormesh() <differences-pcolor-pcolormesh>`.

Examples

See :

Back References

The following pages refer to to this document either explicitly or contain code examples using this.

matplotlib.pyplot.hist2d matplotlib.axes._axes.Axes.hist2d matplotlib.pyplot.pcolormesh matplotlib.axes._axes.Axes.pcolorfast scipy.interpolate._rbfinterp.RBFInterpolator matplotlib.axes._axes.Axes.pcolormesh matplotlib.axes._axes.Axes.pcolor

Local connectivity graph

Hover to see nodes names; edges to Self not shown, Caped at 50 nodes.

Using a canvas is more power efficient and can get hundred of nodes ; but does not allow hyperlinks; , arrows or text (beyond on hover)

SVG is more flexible but power hungry; and does not scale well to 50 + nodes.

All aboves nodes referred to, (or are referred from) current nodes; Edges from Self to other have been omitted (or all nodes would be connected to the central node "self" which is not useful). Nodes are colored by the library they belong to, and scaled with the number of references pointing them


File: /matplotlib/axes/_axes.py#5872
type: <class 'function'>
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