CODEWITHSUNDEEP
pythonpython-3.xnumpymatplotlibscatter-plot
Bogdan Janiszewski
Bogdan Janiszewski

Reputation: 2883

Matplotlib scatter plot with unknown error

I am attempting to create a scatter plot. I have a list of numbers from 0 - 17 as well as an array with 18 values. I can plot the data as a line plot but when I try to plot as a scatter, I get an error message I do not understand:

TypeError: ufunc 'sqrt' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''safe''

What does this error message mean and how can I get the data to plot as a scatter?

import numpy as np
import matplotlib.pyplot as plt

y = [7316.0, 7453.25, 7518.25, 7711.5, 7448.0, 7210.25, 7416.75, 6960.75, 
     7397.75, 6397.5, 5522.75, 5139.0, 5034.75, 4264.75, 5106.0, 3489.5, 
     4712.0, 4770.0]
x = np.arange(0,18,1)

plt.rcParams['legend.loc'] = 'best'
plt.figure(1)
plt.xlim(0, 20)
plt.ylim(0, 10000)
plt.scatter(x, y, 'r')
plt.show()

Upvotes: 51

Views: 48171

Answers (2)

cottontail
cottontail

Reputation: 23429

The third positional argument of plot() is fmt= which takes strings of the format '[marker][line][color]' so that each of lines, colors, and markers can be formatted in one go. If you omit line, it becomes a scatter plot. For example, the following two plot the same graph:

plt.plot(x, y, 'ro');

plt.scatter(x, y, color='r');

Upvotes: 0

gsmafra
gsmafra

Reputation: 2504

Check the scatter documentation. Third argument is for size of points and should be scalar or array_like. I assume 'r' is for color so do the following:

plt.scatter(x, y, c='r')

Upvotes: 97

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