CODEWITHSUNDEEP
pythonnumpymatplotlibplot
isunny
isunny

Reputation: 3

How to plot in python where x-axis values appears more than once, like 0 1 2 3 2 1 0

I'm new to python, and was playing around with it's plotting capability. I wanted to plot Y1 and Y2 where X values go from 10 to 100 with steps of 10, and 100 to 10 with steps of -10.

I was able to plot this using Excel. Here are the X and Y values

X  = [10 20 30 40 50 60 70 80 90 100 100 90 80 70 60 50 40 30 20 10]
Y1 = [0 100 200 300 400 500 600 700 800 900 900 800 700 600 500 400 300 200 100 0]
Y2 = [100 200 300 400 500 600 700 800 900 1000 1000 900 800 700 600 500 400 300 200 100]

How do we plot something like this in python using matplotlib and numpy?

Upvotes: 0

Views: 2385

Answers (2)

tmdavison
tmdavison

Reputation: 69106

Its unclear exactly what you are asking. Do you want the repeated X values to plot on top of each other? In which case, you can use ax.plot as shown in the first example (ax1) below.

If you want the X axis to show all the X values in the order they appear in your list, you could use scatter, then just set the xticklabels to the values in X, as shown in the second example below (ax2)

As stated above in comments, neither of these are particularly difficult: there are lots of examples in the matplotlib gallery.

import matplotlib.pyplot as plt

X  = [10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10]
Y1 = [0, 100, 200, 300, 400, 500, 600, 700, 800, 900, 900, 800, 700, 600, 500, 400, 300, 200, 100, 0]
Y2 = [100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100]

fig = plt.figure()
ax1=plt.subplot(211)
ax2=plt.subplot(212)

# First example: overlap repeated X values
ax1.plot(X,Y1,'ro')
ax1.plot(X,Y2,'bo')
ax1.set_title('ax.plot')

# Second example: keep all X values in sequential order
ax2.scatter(range(len(Y1)),Y1,color='r')
ax2.scatter(range(len(Y2)),Y2,c='b')
ax2.set_title('ax.scatter')
ax2.set_xlim(0,len(Y1)-1)
ax2.set_xticks(range(len(Y1)))
ax2.set_xticklabels(X)

plt.show()

enter image description here

Upvotes: 1

Shubhashis
Shubhashis

Reputation: 10631

Actually you don't HAVE to use numpy to plot with matplotlib. You can use normal python lists for plotting with matplotlib. NumPy is the package for scientific computation with Python. Its used for its great capabilities for handling matrices. Doing the matrix operation with standard lists is slower. That's why numpy is great.

You can read about numpy here!

You can take help from this link for plotting data with pyplot. Tweak around the parameters to see what you find.

Also I am providing this simple code for plotting. I assume you know how to use import in python. 

import matplotlib.pyplot as plt

X = [range(0,100,10)]
Y = [range(0,1000,100)]

plt.scatter(X,Y)
plt.show()

If you insist on using numpy you can change the code of these two portions 

import numpy as np

X = np.array([range(0,100,10)])
Y = np.array([range(0,1000,100)])

Upvotes: 0

Related Questions