Top NumPy Statistical Functions & Distributions

Walker Rowe

NumPy can handle a variety of statistical distributions. It can therefore produce samples from a range of applications. For instance, NumPy can help to make statistical predictions about:

  • The odds of getting seven (i.e winning) in an online game of dice
  • How likely is someone to be smashed by a vehicle
  • What is the likelihood the likelihood that you car is going to fail?
  • What number of people are going to wait in the queue at the counter to purchase groceries?

We present the explanation using examples.

(This video tutorial forms part of the Pandas Guide. Make use of the menu on the right to navigate. )

Randomness and the real work

The NumPy functions do not calculate probabilities. Instead, they draw sample data from the distribution of probabilities for the stats, resulting in an arc. The curve may be narrow and steep, or wide , or even be able to reach a low value in the course of time.

The pattern of the data varies according to the type of statistics:

  • Normal
  • Weibull
  • Poisson
  • Binomial
  • Uniform
  • Etc.

Many of the things that happen in our world are in fact random. For instance, if we throw around nearsightedness, clumsiness and inattention, then the probability that someone will be struck by a car is the same for everyone.

The normal distribution is reflected in this.

When you utilize to use the random()function in programming languages, you’re saying to select from the standard distribution. They will be in a middle which is known as the mean. The sloppiness of the observations is known as”the variability. Like the name suggests, the more it fluctuates, then the variance is high.

Let’s take a look at these distributions.


The arguments in favor of regular distribution include:

  • loc is the term used to describe it.
  • scale is the square root of variance, i.e. the standard deviation
  • Size is the size of the sample or the number of trial. 400 refers to the ability to generate the number 400 randomly. The format is (400,) but could have written 400. This indicates that the numbers could be in more than one dimension. This is just a matter of picking numbers here and not some type of cube or any other dimension.


import numpy as np import matplotlib.pyplot as plt arr = np.random.normal(loc=0,scale=1,size=(400,)) plt.plot(arr)

It is interesting to note that the numbers hover around the median 0, 0:


Weibull is used most commonly in preventive maintenance programs. This is basically the rate of failure in the course of time. For machines such as components for trucks, this is referred to as Time to Failure. Manufacturers release their plans for planning.

A Weibull distribution is characterized by its form along with a the scale parameter. In the same vein as the truck:

  • The shape is the speed it is most likely to break, and the severity of the curve.
  • NumPy doesn’t require scale distribution. Instead, you just divide your Weibull value by the scale to find the distribution of scale.


import numpy as np import matplotlib.pyplot as plt shape=5 arr = np.random.weibull(shape,400) plt.hist(arr)

This histogram displays the number of observations that are unique or frequency distributions:


Poisson refers to the likelihood of a certain amount of people in lines over a certain period of time.

For instance the length of the line at a store is controlled by Poisson distribution. If you know this you are able to continue browsing until the queue becomes shorter, and you will not have to wait. This is because the length of lines is variable, and changes quite a bit, as time goes by. There isn’t a consistent length throughout the day. Also, go shopping or explore the stores instead of standing in the long line.Copy

import matplotlib.pyplot as plt arr = np.random.poisson(2,400) plt.plot(arr)

This is where we can see that the length of the line varies between 8 and zero. The number function doesn’t give any probability. Be aware that it’s an observation, which means it selects a number that is dependent on it. Weibull statistics.


Binomial can be described as discrete outcomes similar to rolling dice.

Let’s take a look at how to play the craps game. You have to roll two dice and you’re rewarded when you score a 7. It is possible to get a 7 by rolling these dice:

  • 1,6
  • 2,5
  • 3,4
  • 4,3
  • 5,2
  • 6,1

In other words, there are six different ways to succeed. There are 6*6*36 chances. Therefore, the probability of winning is 6/16 = 1/6 .

For a simulation of 400 roll dice, make use of:Copy

import numpy as np import matplotlib.pyplot as plt arr = np.random.binomial(36,1/6,400) plt.hist(arr)

The 400 trial 2 6s were used around three times.


Uniform distribution fluctuates with equal frequency between the high and low band.Copy

import numpy as np import matplotlib.pyplot as plt arr = np.random.uniform(-1,0,1000) plt.hist(arr)

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