One of the most common errors you may encounter when using Python is:

NameError: name 'np' is not defined

This error occurs when you import the python library NumPy, but fail to give it the alias of **np** when importing it.

The following examples illustrate how this problem occurs and how to fix it.

**Example 1: import numpy**

Suppose you import the NumPy library using the following code:

import numpy

If you then attempt to define a numpy array of values, you’ll get the following error:

**#define numpy array
x = np.random.normal(loc=0, scale=1, size=20)
#attempt to print values in arrary
print(x)
Traceback (most recent call last):
----> 1 x = np.random.normal(loc=0, scale=1, size=20)
2 print(x)
NameError: name 'np' is not defined
**

To fix this error, you need provide the alias of **np** when importing NumPy:

import numpy as np #define numpy array x = np.random.normal(loc=0, scale=1, size=20) #print values in arrary print(x) [-0.93937656 -0.49448118 -0.16772964 0.44939978 -0.80577905 0.48042484 0.30175551 -0.15672656 -0.26931062 0.38226115 1.4472055 -0.13668984 -0.74752684 1.6729974 2.25824518 0.77424489 0.67853607 1.46739364 0.14647622 0.87787596]

**Example 2: from numpy import ***

Suppose you import all functions from the NumPy library using the following code:

from numpy import *

If you then attempt to define a numpy array of values, you’ll get the following error:

**#define numpy array
x = np.random.normal(loc=0, scale=1, size=20)
#attempt to print values in arrary
print(x)
Traceback (most recent call last):
----> 1 x = np.random.normal(loc=0, scale=1, size=20)
2 print(x)
NameError: name 'np' is not defined
**

To fix this error, you need provide the alias of **np** when importing NumPy:

import numpy as np #define numpy array x = np.random.normal(loc=0, scale=1, size=20) #print values in arrary print(x) [-0.93937656 -0.49448118 -0.16772964 0.44939978 -0.80577905 0.48042484 0.30175551 -0.15672656 -0.26931062 0.38226115 1.4472055 -0.13668984 -0.74752684 1.6729974 2.25824518 0.77424489 0.67853607 1.46739364 0.14647622 0.87787596]

Alternatively, you can choose to not use the **np** syntax at all:

import numpy #define numpy array x = numpy.random.normal(loc=0, scale=1, size=20) #print values in arrary print(x) [-0.93937656 -0.49448118 -0.16772964 0.44939978 -0.80577905 0.48042484 0.30175551 -0.15672656 -0.26931062 0.38226115 1.4472055 -0.13668984 -0.74752684 1.6729974 2.25824518 0.77424489 0.67853607 1.46739364 0.14647622 0.87787596]

**Note:** The syntax “import numpy as np” is commonly used because it offers a more concise way to use NumPy functions. Instead of typing “numpy” each time, you can simply type in “np” which is quicker and easier to read.

**Additional Resources**

How to Fix: NameError name ‘pd’ is not defined

How to Fix: No module named pandas