Plotting a scatter plot from individual points, how to color points from a colormap?

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Using matplotlib, I am trying to produce a scatter plot where points vary in both markers and colors.

import matplotlib.pyplot as plt
import numpy as np

markers = np.array(["1","2","3","4","+",">"])

# Dummy Data
x = np.array([0, 2, 3, 4, 0, 1, 5, 6, 7, 8])
y = np.array([0, 1, 0, 2, 3, 4, 5, 6, 7, 8])
c = np.array([0, 0.4, 0, 0.2, 1, 0.9, 1, 1, 1])
m = np.array([0, 0, 0, 1, 1, 1, 2, 3, 3])

# Figure
fig, ax = plt.subplots(figsize=(8,7))

# Scatter
ax.scatter(x=x, y=y, c=c, marker=markers[m], cmap = 'summer') # Not possible

However, matplotlib does not currently support supplying an array of markers.

So I find myself looping over points, but color does not change.

# Works nice for markers but all points are same color.
for i in range(x.shape[0]):
    ax.scatter(x=x[i], y=y[i], c=c[i], marker=markers[m[i]], cmap = 'summer')

I am not familiar with playing with ColorMap instances and could not find examples that work nicely for what I am trying to achieve.

Optionally, it would be nice to have a colormap with it.

colormap data-visualization matplotlib numpy python
1 Answers

Use the ax.scatter for each point as you're doing in your second block, but combine with a newly created newcmp including the arguments vmin and vmax to map the color array c to the colormap cmap.

import matplotlib.pyplot as plt
import numpy as np
from matplotlib import cm
from matplotlib.colors import ListedColormap

markers = np.array(["1","2","3","4","+",">"])

# Dummy Data
x = np.array([0, 2, 3, 4, 0, 1, 5, 6, 7, 8])
y = np.array([0, 1, 0, 2, 3, 4, 5, 6, 7, 8])
c = np.array([0, 0.4, 0, 0.2, 1, 0.8, 0.9, 1, 1, 1])
m = np.array([0, 0, 0, 1, 1, 2, 3, 4, 5, 3])

# Figure
fig, ax = plt.subplots(figsize=(8,7))

hsv_modified = cm.get_cmap('hsv', 500)
newcmp = ListedColormap(hsv_modified(np.linspace(0.0, 0.3, 500)))

for xi,yi,mi,ci in zip(x,y,m,c):
    ax.scatter(xi,yi,c=ci, marker=markers[mi], s=200, cmap=newcmp, vmin=min(c), vmax=max(c))

plt.show()

scatter_different_markers

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