matplotlib.pyplot.pcolor

matplotlib.pyplot.pcolor(*args, alpha=None, norm=None, cmap=None, vmin=None, vmax=None, data=None, **kwargs) [source]

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

Call signature:

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

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

Hint

pcolor() can be very slow for large arrays. In most cases you should use the similar but much faster pcolormesh instead. See there for a discussion of the differences.

Parameters:	C : array_like A scalar 2-D array. The values will be color-mapped. X, Y : array_like, optional The coordinates of the quadrilateral corners. The quadrilateral for C[i,j] has corners at: (X[i+1, j], Y[i+1, j]) (X[i+1, j+1], Y[i+1, j+1]) +--------+ | C[i,j] | +--------+ (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. The dimensions of X and Y should be one greater than those of C. Alternatively, X, Y and C may have equal dimensions, in which case the last row and column of C will be ignored. If X and/or Y are 1-D arrays or column vectors they will be expanded as needed into the appropriate 2-D arrays, making a rectangular grid. cmap : str or Colormap, optional A Colormap instance or registered colormap name. The colormap maps the C values to colors. Defaults to rcParams["image.cmap"]. norm : 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 : scalar, optional, 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). 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"] will be used. Note that currently rcParams["patch.force_edgecolor"] has to be True for this to work. 'face': Use the adjacent face color. An mpl color or sequence of colors will set the edge color. The singular form edgecolor works as an alias. alpha : scalar, optional, default: None The alpha blending value of the face color, between 0 (transparent) and 1 (opaque). Note: The edgecolor is currently not affected by this. snap : bool, optional, default: False Whether to snap the mesh to pixel boundaries.
Returns:	collection : matplotlib.collections.Collection
Other Parameters:	antialiaseds : bool, optional, default: False The default antialiaseds is False if the default edgecolors="none" is used. This eliminates artificial lines at patch boundaries, and works regardless of the value of alpha. If edgecolors is not "none", then the default antialiaseds is taken from rcParams["patch.antialiased"], which defaults to True. Stroking the edges may be preferred if alpha is 1, but will cause artifacts otherwise. **kwargs Additionally, the following arguments are allowed. They are passed along to the PolyCollection 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 float or None animated bool antialiased or aa or antialiaseds bool or sequence of bools array ndarray capstyle {'butt', 'round', 'projecting'} clim a length 2 sequence of floats; may be overridden in methods that have vmin and vmax kwargs. clip_box Bbox clip_on bool clip_path [(Path, Transform) | Patch | None] cmap colormap or registered colormap name color color or sequence of rgba tuples contains callable edgecolor or ec or edgecolors color or sequence of colors or 'face' facecolor or facecolors or fc color or sequence of colors figure Figure gid str hatch {'/', '\', '|', '-', '+', 'x', 'o', 'O', '.', '*'} in_layout bool joinstyle {'miter', 'round', 'bevel'} label object linestyle or dashes or linestyles or ls {'-', '--', '-.', ':', '', (offset, on-off-seq), ...} linewidth or linewidths or lw float or sequence of floats norm Normalize offset_position {'screen', 'data'} offsets float or sequence of floats path_effects AbstractPathEffect picker None or bool or float or callable pickradius unknown rasterized bool or None sketch_params (scale: float, length: float, randomness: float) snap bool or None transform Transform url str urls List[str] or None visible bool zorder float

See also

pcolormesh

for an explanation of the differences between pcolor and pcolormesh.

imshow

If X and Y are each equidistant, imshow can be a faster alternative.

Notes

Masked arrays

X, Y and C may be masked arrays. If either C[i, j], or one of the vertices surrounding C[i,j] (X or Y at [i, j], [i+1, j], [i, j+1], [i+1, j+1]) is masked, nothing is plotted.

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.

Handling of pcolor() end-cases

pcolor() displays all columns of C if X and Y are not specified, or if X and Y have one more column than C. If X and Y have the same number of columns as C then the last column of C is dropped. Similarly for the rows.

Note: This behavior is different from MATLAB's pcolor(), which always discards the last row and column of C.

Note

In addition to the above described arguments, this function can take a data keyword argument. If such a data argument is given, the following arguments are replaced by data[<arg>]:

• All positional and all keyword arguments.

Objects passed as data must support item access (data[<arg>]) and membership test (<arg> in data).

Examples using matplotlib.pyplot.pcolor