Matplotlib output too small to read - matplotlib

Question

In adjusting the domain of a function to find certain parameters in a matplotlib plot, I found that when I try to isolate the part I need, the output becomes so small that details are impossible to see. I've tried refreshing the kernel with no change and plt.rcParams['figure.figsize'] hasn't been effective either.
This is my current code, with unused options in the function removed.
import numpy as np
import matplotlib.pyplot as plt
def P_cubic(V,T,Tc,Pc,ParamSet,omega=0):
R = 8.31446261815324 #J mol^-1 K^-1
Tr = T/Tc
if ParamSet == 'vdW':
elif ParamSet == 'RK':
elif ParamSet == 'SRK':
elif ParamSet == 'PR':
alpha = (1+(0.37464+1.54226*omega-0.26992*omega**2)*
(1-Tr**(1/2)))**2
sigma = 1+np.sqrt(2)
epsilon = 1-np.sqrt(2)
Omega = 0.07780
Psi = 0.45724
Zc = 0.30740
a = Psi*alpha*R**2*Tc**2/Pc
b = Omega*T*Tc/Pc #m3 mol-1
P = R*T/(V-b)-a/((V+epsilon*b)*(V+sigma*b))
return P
Tc = 512.5 #K
Pc = 8.0840E6 #Pa
omega = 0.565831
T = 473 #K
b = 0.07780*T*Tc/Pc #m3 mol-1
V = np.arange(0,1,0.001)
Vrange = b*V #m3 mol-1
PPa = np.empty(len(Vrange))
for i in range(len(Vrange)):
PPa[i]=P_cubic(Vrange[i],T,Tc,Pc,'PR',omega) #Pa
Pbar = PPa*1.0E-5 #bar
plt.rcParams['figure.figsize']=(1,0.8)
plt.plot(V,Pbar)
plt.xlabel('V/b')
plt.ylabel('P /bar')
plt.xlim(0,np.max(V))
plt.ylim(np.min(Pbar),np.max(Pbar))
plt.title('Variance of Pressure with Volume of Pure Methanol at 473 K')
plt.text(15,-6,f'b = {b:.2E} m^3/mol');
Below are screenshots with the output at varying figsize parameters to show that plt.rcParams['figure.figsize'] is not helping.
How do I fix this so that I can see the details of the plot?

Answer 1

There are two reasons for this. First, the size unit of the graph is inches, so the specified number itself is small, resulting in a smaller graph. Secondly, the default coordinates of the annotations are based on the data, so the x-value is 15, which is far from the graph, so the figure is automatically smaller. So, I think you need to set the graph size and fix the x-value of the annotations.
fig, ax = plt.subplots()
plt.rcParams['figure.figsize']=(8,4)
ax.plot(V,Pbar)
plt.xlabel('V/b')
plt.ylabel('P /bar')
plt.xlim(0,np.max(V))
plt.ylim(np.min(Pbar),np.max(Pbar))
plt.title('Variance of Pressure with Volume of Pure Methanol at 473 K')
plt.text(1.1,-6,f'b = {b:.2E} m^3/mol')
#plt.text(1.1,-6,f'b = {b:.2E} m^3/mol', transform=ax.transData)
plt.show()