syrte
10/29/2016 - 1:14 PM

Make a histogram-like step plot.

Make a histogram-like step plot.

``````from __future__ import division, print_function, absolute_import
import numpy as np
from matplotlib import pyplot as plt

def steps(x, y, *args, **kwargs):
'''steps(x, y, *args, style='line', bottom=0, **kwargs)
Make a step plot.
The interval from x[i] to x[i+1] has level y[i]
This function is useful for show the results of np.histogram.

Parameters
----------
style : ['line' | 'step' | 'filled' | 'bar'], optional
The type of steps to draw.
- 'line': step line plot
- 'step': step line with vertical line at borders.
- 'filled': filled step line plot
bottom: float
The bottom baseline of the plot.
args, kwargs:
same as those for
`matplotlib.pyplot.plot` if `style` in ['line', 'step'], or
`matplotlib.pyplot.plot.fill` if `style` in ['filled', 'bar'].

Example
-------
np.random.seed(4)
b = np.linspace(0.1, 0.9, 6)
for i, style in enumerate(['line', 'step', 'filled', 'bar']):
a = np.random.rand(50) + i
steps(*np.histogram(a, b + i)[::-1], style=style,
lw=2, zorder=i)
plt.text(i+0.5, 14, style)
plt.xlim(0, 4)
plt.ylim(-1, 16)
'''
m, n = len(x), len(y)
if m == n:
kwargs.setdefault("where", "mid")
return plt.step(x, y, *args, **kwargs)
elif m != n + 1:
raise ValueError

style = kwargs.pop('style', 'line')
bottom = kwargs.pop('bottom', 0)
kwargs.pop('drawstyle', None)
kwargs.pop('where', None)

if style == 'line':
x, y = np.repeat(x, 2), np.repeat(y, 2)
x = x[1:-1]
elif style in ['step', 'filled']:
x, y = np.repeat(x, 2), np.repeat(y, 2)
y = np.hstack([bottom, y, bottom])
elif style == 'bar':
x, y = np.repeat(x, 3), np.repeat(y, 3)
x = x[1:-1]
y = np.hstack([y, bottom])
y[::3] = bottom
else:
raise ValueError("not surpport style: %s" % style)

if style in ['line', 'step']:
return plt.plot(x, y, *args, **kwargs)
else:
return plt.fill(x, y, *args, **kwargs)
``````