Pyplot matplotlib

Posted on September 2, 2022

Tags: codeetc

1 plt

import matplotlib.pyplot as plt
import numpy as np
arr = np.arange(6)
plt.plot(arr) # plot the points in the array a
plt.title("My first fitgure")
plt.xlabel("my x-axis")
plt.ylabel("y")
plt.show()

2 single subplots()

Everytime we need to plot we must reinstantiate object with plt.subplots()

fig, ax = plt.subplots()
ax.plot(...) 
plt.show() 

fig, ax = plt.subplots() 
ax.plot(...)
plt.show()

fig, ax = plt.subplots()
ax.set_xlabel("sigma aka Std")
ax.set_ylabel("Prob")
ax.plot(..)
plt.show()

3 multiplot subplot

fig,ax = plt.subplots(2,2)
ax[0,0].plot(arr) #top left
ax[0,1].plot(arr) #top right
ax[1,0].plot(arr)
ax[1,1].plot(arr)
fig.show()

painting=plt.imread("painting.png")
plt.imshow(painting)
plt.imshow(painting[:,::-1]) #mirror image in x direction

4 subplots quirk - axes can be: non-array, 1D, 2D

axes parameter is usually a 2d array ax[2,3].plot(arr)

When using subplots for (1,1) which is 1 graph, axes parmeter is not an array of subplots but a single plot ax.plot(arr)

fig,ax = plt.subplots(1,1) #this same as line below
#fig,ax = plt.subplots()

ax[0,0].plot(arr) ###WILL RETURN ERROR
ax.plot(arr) ###OK
fig.show()

When using subplots where any parameter is (n,1) or (1,n), the axes parameter is a single array. ax[3].plot(arr)

fig,ax = plt.subplots(1,2) #this same as line below

ax[0,0].plot(arr) ###WILL RETURN ERROR

ax[0].plot(arr) ###OK
ax[1].plot(arr)
fig.show()