How to Fix – NameError: name ‘array’ is not defined

If you are a Python developer, you may have encountered the error message “NameError name ‘array’ is not defined” while working with the array module in Python. In this tutorial, we will explore the possible causes of this error and provide step-by-step instructions on how to fix it.

We will cover common causes of the error and provide solutions to help you get your code up and running quickly. So, let’s get started!

Why does the NameError: name 'array' is not defined error occur?

This error occurs when you try to use the array library in your Python code, but Python cannot find the array module in its namespace. The following are some of the scenarios in which this error usually occurs.

1. You have not imported the array module.
2. You have imported the array module using a different name.

How to fix the NameError: name 'array' is not defined?

The array module in Python provides a way to store and manipulate arrays of data more efficiently than using a list. Since this library is part of the Python Standard Library, you don’t need to separately install it. You can simply import it and start using it.

It allows you to create arrays of a specific data type, such as integers or floats, and perform operations on them as a whole. The array module is particularly useful when dealing with large amounts of numerical data, as it can be much faster and more memory-efficient than using a list.

Let’s now look at the above scenarios that may result into the above error in detail.

The array module is not imported

It can happen that you are trying to use the array module without even importing it. This is because Python does not recognize the array library and its functions until it is imported into the code.

For example, let’s try to use the array module without importing it and see what we get.

# note that the array module is not imported

# create an array of integers
my_array = array.array('i', [1, 2, 3, 4, 5])

# print the array
print(my_array)

Output:

---------------------------------------------------------------------------

NameError                                 Traceback (most recent call last)

Cell In[1], line 4
      1 # note that the array module is not imported
      2 
      3 # create an array of integers
----> 4 my_array = array.array('i', [1, 2, 3, 4, 5])
      6 # print the array
      7 print(my_array)

NameError: name 'array' is not defined

We get a NameError stating that the name array is not defined. To use the array library, you need to import it first.

import array

# create an array of integers
my_array = array.array('i', [1, 2, 3, 4, 5])

# print the array
print(my_array)

Output:

array('i', [1, 2, 3, 4, 5])

Here, we are importing the array module first and then using it to create an array of integers. You can see that we did not get any errors here.

Note that the array() function is defined in the array module. This could be confusing because they both have the same name. If you want to use the array() function, you can either use the above syntax of importing the entire array module and then using array.array() function or you could only import the array() function like in the example below.

from array import array

# create an array of integers
my_array = array('i', [1, 2, 3, 4, 5])

# print the array
print(my_array)

Output:

array('i', [1, 2, 3, 4, 5])

We get the same result.

The array module is imported using a different name

If you import the array module using a different name, for example import array as arr, and then try to use the name “array” to use it, you will get a NameError because the name “array” is not defined in your current namespace.

Let’s look at an example.

import array as arr

# create an array of integers
my_array = array.array('i', [1, 2, 3, 4, 5])

# print the array
print(my_array)

Output:

---------------------------------------------------------------------------

NameError                                 Traceback (most recent call last)

Cell In[1], line 4
      1 import array as arr
      3 # create an array of integers
----> 4 my_array = array.array('i', [1, 2, 3, 4, 5])
      6 # print the array
      7 print(my_array)

NameError: name 'array' is not defined

We get a NameError: name 'array' is not defined. This is because we have imported the array module with the name arr but we’re trying to use it using the name array.

To fix this error, you can either access array using the name that you have used in the import statement or import array without an alias.

import array as arr

# create an array of integers
my_array = arr.array('i', [1, 2, 3, 4, 5])

# print the array
print(my_array)

Output:

array('i', [1, 2, 3, 4, 5])

In the above example, we are importing array as arr and then using arr to access the array module’s methods.

Alternatively, as seen in the example in the previous section, you can import array without any aliases and simply use array to avoid the NameError.

Side Note – Consider using Numpy arrays

If you are working with arrays in Python beyond the basic array operations, you might want to consider using Numpy arrays instead. Numpy arrays are faster, more memory-efficient, have more functionality, and support vectorized operations. The array module in the standard library has a more limited set of functionality.

Conclusion

In conclusion, encountering a NameError: name 'array' is not defined error can be frustrating, but it is a common issue that can be easily fixed. By ensuring that the array module is imported correctly and that the correct syntax is used when calling its functions, you can avoid this error and successfully execute your code.

You might also be interested in –

• Different ways to Create NumPy Array
• How to Fix – NameError name ‘copy’ is not defined
• How to Fix – NameError name ‘pprint’ is not defined