Increment matplotlib color cycle

Question

Is there a simple way to increment the matplotlib color cycle without digging into axes internals?

When plotting interactively a common pattern I use is:

Answer 1

Similar to the other answers but using matplotlib color cycler:

import matplotlib.pyplot as plt
from itertools import cycle

prop_cycle = plt.rcParams['axes.prop_cycle']
colors = cycle(prop_cycle.by_key()['color'])
for data in my_data:
    ax.plot(data.x, data.y, color=next(colors))

Answer 2

You could call

ax2._get_lines.get_next_color()

to advance the color cycler on color. Unfortunately, this accesses the private attribute ._get_lines, so this is not part of the official public API and not guaranteed to work in future versions of matplotlib.

A safer but less direct way of advance the color cycler would be to plot a null plot:

ax2.plot([], [])

---

import numpy as np
import matplotlib.pyplot as plt

x = np.arange(10)
y1 = np.random.randint(10, size=10)
y2 = np.random.randint(10, size=10)*100
fig, ax = plt.subplots()
ax.plot(x, y1, label='first')
ax2 = ax.twinx()
ax2._get_lines.get_next_color()
# ax2.plot([], [])
ax2.plot(x,y2, label='second')

handles1, labels1 = ax.get_legend_handles_labels()
handles2, labels2 = ax2.get_legend_handles_labels()
ax.legend(handles1+handles2, labels1+labels2, loc='best')  

plt.show()

Answer 3

There are several colour schemes available in Pyplot. You can read more on the matplotlib tutorial Specifying Colors.

From these docs:

a "CN" color spec, i.e. 'C' followed by a number, which is an index into the
default property cycle (matplotlib.rcParams['axes.prop_cycle']); the indexing
is intended to occur at rendering time, and defaults to black if the cycle
does not include color.

You can cycle through the colour scheme as follows:

fig, ax = plt.subplots()

# Import Python cycling library
from itertools import cycle

# Create a colour code cycler e.g. 'C0', 'C1', etc.
colour_codes = map('C{}'.format, cycle(range(10)))

# Iterate over series, cycling coloour codes
for y in my_data:
    ax.plot(x, y, color=next(color_codes))

This could be improved by cycling over matplotlib.rcParams['axes.prop_cycle'] directly.