Matplotlib >1 Line Style, Same Line, Different Colors per Line

Question

Given the following data frame and line graph:

import matplotlib.pyplot as plt
from cycler import cycler
import numpy as np
fig, ax=plt.subplots(1)
d=pd.DataFrame({'a':[1,2,3,4],
                'b':[2,3,4,5],
                'c':[3,4,5,6]})
colors=['r','g','b']
ax.set_prop_cycle(cycler('color', [colors]))
ax.plot(d[:3],'-ko',d[2:],'--ko')
plt.show()

You'll notice that I am trying to assign one color per line but it is not working. I also tried using the colors argument in ax.plot. It seems like this should be straight forward.

Thanks in advance for any help on this.

Answer 1

There are two problems in your code.

1. the 'k' in '-ko' and '--ko' sets the colour to black, so we need to remove that

2. colors is already a list, but you have put it inside square brackets again in the call to set_prop_cycle, and thus made it into a nested list: [['r','g','b']]. Remove the square brackets there and it all works fine: ax.set_prop_cycle(cycler('color', colors))

So, your code will look like:

import matplotlib.pyplot as plt
import pandas as pd
from cycler import cycler
import numpy as np
fig, ax=plt.subplots(1)
d=pd.DataFrame({'a':[1,2,3,4],
                'b':[2,3,4,5],
                'c':[3,4,5,6]})
colors=['r','g','b']
ax.set_prop_cycle(cycler('color', colors))
ax.plot(d[:3],'-o',d[2:],'--o')
plt.show()