How to cycle through both colours and linestyles on a matplotlib figure?

Question

I have a bunch of graphs each with around 15 to 20 lines on each. I would like to cycle through colours and linestyles to get many unique lines. If I am using 6 colours and 4 linestyles there should be 20 unique lines, however the code below only produces 6. What am I doing wrong?

Here is a fake data set

import matplotlib.pyplot as plt
from cycler import cycler
import numpy
import seaborn
seaborn.set_style('white')

x = range(10)
ys = []
for i in range(20):
    ys.append(numpy.random.uniform(1, 10, size=10)*i)

This is what I can glean from other posts:

plt.rc('axes', prop_cycle=(cycler('color', ['r', 'g', 'b', 'y', 'c', 'k']) +
                           cycler('linestyle', ['-', '--', ':', '-.', '-', '--'])))

Note I have used duplicates in the linestyle cycler otherwise we get ValueError.

And plotting

plt.figure()
for i in range(20):
    plt.plot(x, ys[i], label=i)
plt.legend(loc=(1, 0.1))
plt.show()

Answer 1

You probably want to multiply the two cyclers:

plt.rc('axes', prop_cycle=(cycler('color', ['r', 'g', 'b', 'y', 'c', 'k']) *
                           cycler('linestyle', ['-', '--', ':', '-.'])))

as stated here, the addition cycles both color and linestyle simultaneously, while the multiplication mixes all properties.

In this case you don't have to use duplicated linestyles, as color and linestyle don't have to have equal cycle length.

Answer 2

As already mentioned by @datasailor you should multiply both cycles:

cycler_op1 = cycler('color', ['r', 'g', 'b', 'y', 'c', 'k']) \
            * cycler('linestyle', ['-', '--', ':', '-.', '-', '--'])

cycler_op2 = cycler('linestyle', ['-', '--', ':', '-.', '-', '--']) \
            * cycler('color', ['r', 'g', 'b', 'y', 'c', 'k'])

rc('axes', prop_cycle = cycler_op1 ) # or cycler_op2

Note that multiplication is not commutative and you get different result. Basically, in the first case the color is fixed and the linestyle changes. In the second case the linestyle is fixed and the color changes. In total 6x6 = 36 possibilities.

With such a large number of curves you may experiment with more colors and linestyles.

ls_cycler = cycler('linestyle',
                    [(0,()), # solid 
                     (0, (1, 10)), # loosely dotted
                     (0, (1, 5)), # dotted
                     (0, (1, 1)), # densely dotted
                     (0, (5, 10)), # loosely dashed
                     (0, (5, 5)), # dashed
                     (0, (5, 1)), # densely dashed
                     (0, (3, 10, 1, 10)), # loosely dashdotted
                     (0, (3, 5, 1, 5)), # dashdotted
                     (0, (3, 1, 1, 1)), # densely dashdotted
                     (0, (3, 10, 1, 10, 1, 10)), # loosely dashdotdotted
                     (0, (3, 5, 1, 5, 1, 5)), # dashdotdotted
                     (0, (3, 1, 1, 1, 1, 1))] # densely dashdotdotted
                  )

color_cycler = cycler('color', [plt.get_cmap('jet')(i/13) for i in range(13)] )

new_cycler = color_cycler + ls_cycler

Result looks like this: