matplotlib.pyplot.pcolormesh   matplotlib.pyplot.pcolormesh(*args, alpha=None, norm=None, cmap=None, vmin=None, vmax=None, shading=None, antialiased=False, data=None, **kwargs)[source]
 
Create a pseudocolor plot with a non-regular rectangular grid. Call signature: pcolormesh([X, Y,] C, **kwargs)
 X and Y can be used to specify the corners of the quadrilaterals.  Hint pcolormesh is similar to pcolor. It is much faster and preferred in most cases. For a detailed discussion on the differences see Differences between pcolor() and pcolormesh().   Parameters 
 
C2D array-like


The color-mapped values.  
X, Yarray-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 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.  
cmapstr or Colormap, default: rcParams["image.cmap"] (default: 'viridis')


A Colormap instance or registered colormap name. The colormap maps the C values to colors.  
normNormalize, 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, vmaxfloat, 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: rcParams["patch.edgecolor"] (default: 'black') will be used. Note that currently rcParams["patch.force_edgecolor"] (default: False) 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.  
alphafloat, 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 rcParams["pcolor.shading"] (default: 'auto'). 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 pcolormesh grids and shading for more description.  
snapbool, default: False


Whether to snap the mesh to pixel boundaries.  
rasterizedbool, optional


Rasterize the pcolormesh when drawing vector graphics. This can speed up rendering and produce smaller files for large data sets. See also Rasterization for vector graphics.    Returns 
 matplotlib.collections.QuadMesh
  Other Parameters 
 
dataindexable 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 QuadMesh constructor:   
Property Description   
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        See also  pcolor

An alternative implementation with slightly different features. For a detailed discussion on the differences see Differences between pcolor() and pcolormesh().  imshow

If X and Y are each equidistant, imshow can be a faster alternative.    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 pcolor if you need this functionality. 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. 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 pcolor returns a PolyCollection, 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 pcolor and pcolormesh support masked arrays for C. However, only pcolor supports masked arrays for X and Y. The reason lies in the internal handling of the masked values. pcolor leaves out the respective polygons from the PolyCollection. 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 pcolor is not drawn as the corresponding polygons do not exist in the PolyCollection. Another difference is the support of Gouraud shading in pcolormesh, which is not available with pcolor.