matplotlib.github.com/3.6.0/gallery/misc/histogram_path.py at main · matplotlib/matplotlib.github.com · GitHub

History

97 lines (79 loc) · 2.84 KB

Raw

"""

========================================================

Building histograms using Rectangles and PolyCollections

========================================================

Using a path patch to draw rectangles.

The technique of using lots of Rectangle instances, or

the faster method of using PolyCollections, were implemented before we

had proper paths with moveto/lineto, closepoly etc in mpl. Now that

we have them, we can draw collections of regularly shaped objects with

homogeneous properties more efficiently with a PathCollection. This

example makes a histogram -- it's more work to set up the vertex arrays

at the outset, but it should be much faster for large numbers of

objects.

"""

import numpy as np

import matplotlib.pyplot as plt

import matplotlib.patches as patches

import matplotlib.path as path

fig, ax = plt.subplots()

# Fixing random state for reproducibility

np.random.seed(19680801)

# histogram our data with numpy

data = np.random.randn(1000)

n, bins = np.histogram(data, 50)

# get the corners of the rectangles for the histogram

left = bins[:-1]

right = bins[1:]

bottom = np.zeros(len(left))

top = bottom + n

# we need a (numrects x numsides x 2) numpy array for the path helper

# function to build a compound path

XY = np.array([[left, left, right, right], [bottom, top, top, bottom]]).T

# get the Path object

barpath = path.Path.make_compound_path_from_polys(XY)

# make a patch out of it

patch = patches.PathPatch(barpath)

ax.add_patch(patch)

# update the view limits

ax.set_xlim(left[0], right[-1])

ax.set_ylim(bottom.min(), top.max())

plt.show()

#############################################################################

# It should be noted that instead of creating a three-dimensional array and

# using `~.path.Path.make_compound_path_from_polys`, we could as well create

# the compound path directly using vertices and codes as shown below

nrects = len(left)

nverts = nrects*(1+3+1)

verts = np.zeros((nverts, 2))

codes = np.ones(nverts, int) * path.Path.LINETO

codes[0::5] = path.Path.MOVETO

codes[4::5] = path.Path.CLOSEPOLY

verts[0::5, 0] = left

verts[0::5, 1] = bottom

verts[1::5, 0] = left

verts[1::5, 1] = top

verts[2::5, 0] = right

verts[2::5, 1] = top

verts[3::5, 0] = right

verts[3::5, 1] = bottom

barpath = path.Path(verts, codes)

#############################################################################

# .. admonition:: References

# The use of the following functions, methods, classes and modules is shown

# in this example:

# - `matplotlib.patches`

# - `matplotlib.patches.PathPatch`

# - `matplotlib.path`

# - `matplotlib.path.Path`

# - `matplotlib.path.Path.make_compound_path_from_polys`

# - `matplotlib.axes.Axes.add_patch`

# - `matplotlib.collections.PathCollection`

# This example shows an alternative to

# - `matplotlib.collections.PolyCollection`

# - `matplotlib.axes.Axes.hist`

matplotlib.github.com/3.6.0/gallery/misc/histogram_path.py at main · matplotlib/matplotlib.github.com · GitHub

Expand file tree

Breadcrumbs

histogram_path.py

Latest commit

History

Breadcrumbs

histogram_path.py

File metadata and controls