by In this post, we explain how to plot in Python. We also explain how to
- Adjust the plot size, and font size
- Adjust the plotting parameters: line width and color, axis labels, marker shape and size, axis limits, etc.
- Plot single and multi plots.
The YouTube video accompanying this post is given below.
We will use Python’s Matplotlib library.
First, we define the functions that we will plot.
1 2 3 4 5 6 7 8 | import numpy as npimport matplotlib.pyplot as plt x=np.linspace(-10,10,500)y11=np.sin(x)y12=np.cos(x)y21=np.exp(-0.1*x)*np.cos(x)y22=np.exp(-0.1*x)*np.sin(x) |
Here is the code for crating a single plot of function y11 defined above and adjusting the plotting parameters:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | # Single plot# adjust the figure sizeplt.figure(figsize=(12, 5))# plot the figure and adjust the plot parametersplt.plot(x,y11,color='blue',linestyle='--',label='sin(x)',marker='o',linewidth=4, markersize=3)# adjust the axis limitsplt.xlim(-1,10)plt.ylim(-1,1)# insert the titleplt.title('Function Plot', fontsize=14)# set the axis labelsplt.xlabel('x',fontsize=14)plt.ylabel('sin(x)',fontsize=14)# adjust the font size of x and y axesplt.tick_params(axis='both', which='major', labelsize=14)# insert legendplt.legend(fontsize=14)# save figureplt.savefig('saved_figure.png')plt.show() |
This code is self-explanatory. The code produces the file “saved_figure.png”, that is shown below
Next, we explain how to plot several subplots on the same graph. We plot all 4 defined functions:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | # Subplots defined by a 2x2 matrix# define the subplot matrix and define the sizefig, ax = plt.subplots(2,2,figsize=(15,8))ax[0,0].plot(x,y11,color='green',linestyle='-',linewidth=3,label='sin(x)')ax[0,0].set_xlabel("x",fontsize=14)ax[0,0].set_ylabel("sin(x)",fontsize=14)ax[0,0].tick_params(axis='both',labelsize=12)ax[0,0].legend(fontsize=14)ax[0,1].plot(x,y12,color='blue', linestyle='--',linewidth=3)ax[1,0].plot(x,y21, color='black', linestyle= '-.',linewidth=3)ax[1,1].plot(x,y22, color= 'magenta', linestyle=':',linewidth=3)ax[1,1].set_xlim(0,1)ax[1,1].set_ylim(-1,1) fig.savefig('subplots.png') |
A few comments are in order. The code line : “fig, ax = plt.subplots(2,2,figsize=(15,8))”, specifies the plotting matrix and the figure size. In this case we will create a plot consisting of the 2×2 subplots. This function returns the object “ax”. If we want to plot at the sunplot (0,0), we select this plot by typing ax[0,0], and then calling the plotting function. Other code lines are self-explanatory. These code lines produce the plot shown below.
