What is the binom.pmf() method in Python?
The binom.pmf function is a part of Python’s SciPy library and is used to model probabilistic experiments with the help of binomial distribution.
To use the binom.pmf function, you must import scipy at the very start of the program:
from scipy.stats import binom
Syntax
The binom.pmf method has the following syntax:
scipy.stats.binom.pmf(r,n, p)
Parameters
The binom.pmf function takes in three parameters:
n: the total number of trials or times the experiment will be carried out.r: a list of integers from 0 ton, inclusive.p: the probability that the outcome of a single experiment will be a success. The value ofpmust be between 0 and 1, inclusive.
Binomial distribution is used to model experiments that have only one of two outcomes, success or failure.
Return value
The binom.pmf method returns a list with the same number of values and sequence as r. The return value is the probability mass function for the values in r.
Example
The code below shows how to use the binom.pmf function in Python.
First, we set the values of n and p to 10 and 0.35, respectively. This is to denote that the experiment will be carried out 10 times, and the probability that the outcome of a single experiment is a success is 0.35.
Next, we call the binom.pmf function and print its return value with the print function. The return value is a list of 10 values, which corresponds to the probability for 0-10 trials of the experiment being a success. For example, the first value corresponds to the probability for none of the 10 experiments being a success, and the last value corresponds to the probability for all 10 experiments being a success.
Since all of the values in the returned list are probabilities, any value in this list and its numerical difference from 1 must sum to 1. We affirm our observation with the
forloop at the end of the snippet.
from scipy.stats import binomimport matplotlib.pyplot as plt# setting the values# of n and pn = 10p = 0.35#defining list of r valuesr= list(range(n + 1))#calling the binom.pmf function and printing its return valuereturn_val=binom.pmf(r, n, p)print('Return Value:')print(return_val)#print the sum of 1-return_value[i] and return_value[i]print("Loop to attest our observation:")for i in range(0,n+1):print(return_val[i]+1-return_val[i])
