python-scipyHow do I use the Python Scipy binom function?

The scipy.stats.binom function is a part of the SciPy library and is used to calculate the probability mass function (PMF) or cumulative density function (CDF) of a binomial distribution. A binomial distribution is a statistical distribution used to model the probability of a given number of successes in a set number of independent trials.

Example code

from scipy.stats import binom

# Calculate the probability of getting exactly 3 heads in 10 coin flips
binom.pmf(3, 10, 0.5)

Output example

0.11718750000000006

The code above calculates the probability mass function (PMF) of a binomial distribution with 10 trials and a probability of success of 0.5. The probability of getting exactly 3 heads in 10 coin flips is 0.11718750000000006.

The scipy.stats.binom function can also be used to calculate the cumulative density function (CDF) of a binomial distribution.

Example code

from scipy.stats import binom

# Calculate the probability of getting 3 or fewer heads in 10 coin flips
binom.cdf(3, 10, 0.5)

Output example

0.998046875

The code above calculates the cumulative density function (CDF) of a binomial distribution with 10 trials and a probability of success of 0.5. The probability of getting 3 or fewer heads in 10 coin flips is 0.998046875.

Code explanation

• from scipy.stats import binom: this imports the binom function from the SciPy library.
• binom.pmf(3, 10, 0.5): this calculates the probability mass function (PMF) of a binomial distribution with 10 trials and a probability of success of 0.5, and returns the probability of getting exactly 3 successes.
• binom.cdf(3, 10, 0.5): this calculates the cumulative density function (CDF) of a binomial distribution with 10 trials and a probability of success of 0.5, and returns the probability of getting 3 or fewer successes.

Helpful links

• SciPy Documentation
• Wikipedia - Binomial Distribution

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