Changing colors for data points in Matplotlib

Question

I am plotting an array A which has len(A)=2. I want to plot A[0],A[1] with separate colors on the same graph, not a single color as shown in the current output and also add legends for each A[0],A[1].

import numpy as np
import matplotlib.pyplot as plt


A=np.array([[[0.02109   ],
       [0.02109   ],
       [0.0201082 ],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ],
       [0.02055473],
       [0.02055797],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ]],
       
       [[0.02109   ],
       [0.02109   ],
       [0.01127196],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ],
       [0.01573726],
       [0.01576968],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ]]])



plt.title("Line graph")
for i in range(0,len(A)):
    plt.plot(A[i], color="red", ls='', marker='o')
plt.xlabel('Node number')
plt.ylabel('IFT (mN/m)')

The current output is

Does this answer your question? [How to change data points color based on some variable](https://stackoverflow.com/questions/7881994/how-to-change-data-points-color-based-on-some-variable) — medium-dimensional, Jan 03 '23 at 08:01
Can you use a scatter plot instead of a plot ? With this, you will be able to to it (and also you can remove your loop iteration if you create a dictionary of colors and legends before) — Only god knows, Jan 03 '23 at 09:44

score 1 · Accepted Answer · answered Jan 03 '23 at 09:57

If I am understating well your question, I would suggest to use plot.scatter, and also to remove the loop for plotting (which is faster in python if your A array is bigger), such as the following (vec_x is a vector with the corresponding index according to the shape of your matrix):

vec_x = np.arange(np.shape(A)[1])
plt.scatter(vec_x, A[0], c='r', label='A[0]')
plt.scatter(vec_x, A[1], c='b', label='A[1]')
plt.legend()

Evgeny Romensky · Answer 2 · 2023-01-03T10:26:47.383

0

You can try to draw plots separately:

import numpy as np
import matplotlib.pyplot as plt   

A=np.array([[[0.02109   ],
       [0.02109   ],
       [0.0201082 ],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ],
       [0.02055473],
       [0.02055797],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ]],
       
       [[0.02109   ],
       [0.02109   ],
       [0.01127196],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ],
       [0.01573726],
       [0.01576968],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ]]])



plt.title("Line graph")
for i in range(0,len(A[0])):
    plt.plot(i, A[0][i], color = 'red', ls='', marker='o')
    plt.plot(i, A[1][i], color = 'blue', ls='', marker='o')
plt.xlabel('Node number')
plt.ylabel('IFT (mN/m)')
plt.legend([1, 2])
plt.show()

edited Jan 03 '23 at 10:26

answered Jan 03 '23 at 09:31

Evgeny Romensky

97
7

and about legend? – Shounak Das Jan 03 '23 at 09:39
1

Sorry. I forgot. This time with legend – Evgeny Romensky Jan 03 '23 at 10:00
I want to have one color for ```A[0]```, another color for ```A[1]```. Not different colors for each point. – jcbose123 Jan 03 '23 at 10:13
The same result as 'Only god knows' but with plot function – Evgeny Romensky Jan 03 '23 at 10:28

score 0 · Answer 3 · answered Jan 03 '23 at 10:01

You can make a list of color and assign it for A[i] in for loop. And for legend you need to add label, If you can also do this like the previous one but I did it like this label= A[i] so final code should be: import numpy as np import matplotlib.pyplot as plt

A=np.array([[[0.02109   ],
       [0.02109   ],
       [0.0201082 ],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ],
       [0.02055473],
       [0.02055797],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ]],
       
       [[0.02109   ],
       [0.02109   ],
       [0.01127196],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ],
       [0.01573726],
       [0.01576968],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ],
       [0.02109   ]]])


color_dot = ["blue", "red"]
plt.title("Line graph")
for i in range(0,len(A)):
    plt.plot(A[i], color= color_dot[i], ls='', marker='o', label= A[i])
    
plt.legend()
plt.xlabel('Node number')
plt.ylabel('IFT (mN/m)')

Changing colors for data points in Matplotlib

3 Answers3