ValueError: Number of rows must be a positive integer, not 3.0-CodePudding

I have this code:

import numpy as np
from scipy import stats
from matplotlib import pyplot as plt

if __name__ == "__main__":
   # Create a list of the number of coin tosses ("Bernoulli trials")
   number_of_trials = [0, 2, 10, 20, 50, 500]
   # Conduct 500 coin tosses and output into a list of 0s and 1s
   # where 0 represents a tail and 1 represents a head
   data = stats.bernoulli.rvs(0.5, size=number_of_trials[-1])
   # Discretise the x-axis into 100 separate plotting points
   x = np.linspace(0, 1, 100)
   # Loops over the number_of_trials list to continually add
   # more coin toss data. For each new set of data, we update
   # our (current) prior belief to be a new posterior. This is
   # carried out using what is known as the Beta-Binomial model.
   # For the time being, we won’t worry about this too much.
   for i, N in enumerate(number_of_trials):
       # Accumulate the total number of heads for this
       # particular Bayesian update
       heads = data[:N].sum()
       # Create an axes subplot for each update
       ax = plt.subplot(len(number_of_trials) / 2, 2, i   1)
    
       ax.set_title("%s trials, %s heads" % (N, heads))
       # Add labels to both axes and hide labels on y-axis
       plt.xlabel("$P(H)$, Probability of Heads")
       plt.ylabel("Density")
       if i == 0:
          plt.ylim([0.0, 2.0])
       plt.setp(ax.get_yticklabels(), visible=False)

       # Create and plot a Beta distribution to represent the
       # posterior belief in fairness of the coin.
       y = stats.beta.pdf(x, 1   heads, 1   N - heads)
       plt.plot(x, y, label="observe %d tosses,\n %d heads" % (N, heads))
       plt.fill_between(x, 0, y, color="#aaaadd", alpha=0.5)
       # Expand plot to cover full width/height and show it
       plt.tight_layout()
       plt.show()

I get the error in this line: ax = plt.subplot(len(number_of_trials) / 2, 2, i 1) ValueError: Number of rows must be a positive integer, not 3.0

I tried to set int(number_of_trials) without success

Any ideas?

CodePudding user response：

You need to cast whole len(number_of_trials) / 2 as an int.

ax = plt.subplot(int(len(number_of_trials) / 2), 2, i   1)

This solves the error.