CODEWITHSUNDEEP
pythonmatplotlibplotlinegraph
Matthew Pardo
Matthew Pardo

Reputation: 11

Strange Line Graph Output - Python

I'm fairly new to Python and I've come up with an issue on a plot. Can someone explain why this line graph would connect this way? It seems like I am missing a key step in sorting the variables.

To clarify, if the data was set up in this fashion, how would one get a line graph with the points (1,2) moving diagonal to (2,5), down diagonal to (3,1) and then moving up to (4,2) and (5,4)?

import matplotlib.pyplot as plt

a = [3,1,5,4,2]

b = [1,2,4,2,5]

plt.plot(a, b)

displayed plot

Upvotes: 0

Views: 177

Answers (1)

Kirk Broadhurst
Kirk Broadhurst

Reputation: 28708

It appears as if line is simply joining your observations in the order presented; starting at (3,1) then to (1,2) and so on. This makes sense, maybe it's what someone would want, and should be easy enough to fix - just sort your data such that the X value is increasing.

It's easy to sort your a value; the catch is sorting your b value in the same way. To do this I'd zip the two together, sort, then unpack.

import matplotlib.pyplot as plt

b = [t[1] for t in sorted(zip(a, b))]
a = sorted(a)

plt.plot(a, b)

Upvotes: 1

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