matplotlib.pyplot.pcolor

matplotlib.pyplot.pcolor(*args, shading=None, 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 Differences between pcolor() and pcolormesh() for a discussion of the differences.

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', the dimensions of X and Y should be the same as those of C (if not, a ValueError will be raised). The color C[i, j] will be centered on (X[i, j], Y[i, j]).

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.

shading{'flat', 'nearest', '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.

  • '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.

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:

The singular form edgecolor works as an alias.

alphafloat, 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.

snapbool, default: False

Whether to snap the mesh to pixel boundaries.

Returns
matplotlib.collections.Collection
Other Parameters
antialiasedsbool, 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"] (default: True). Stroking the edges may be preferred if alpha is 1, but will cause artifacts otherwise.

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 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

array-like or scalar or None

animated

bool

antialiased or aa or antialiaseds

bool or list of bools

array

array-like or None

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

offsets

(N, 2) or (2,) array-like

path_effects

AbstractPathEffect

paths

list of array-like

picker

None or bool or float or callable

pickradius

float

rasterized

bool

sizes

ndarray or None

sketch_params

(scale: float, length: float, randomness: float)

snap

bool or None

transform

Transform

url

str

urls

list of str or None

verts

list of array-like

verts_and_codes

unknown

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.