Fix AttributeError: ‘numpy.ndarray’ object has no attribute ‘append’ for Beginners – NumpPy Tutorial

If you plan to insert a value to the end of a numpy.ndarray, you will get an error: AttributeError: ‘numpy.ndarray’ object has no attribute ‘append’. In this tutorial, we will introduce how to fix this error.

Here is an example:

import numpy as np

data = np.array([1,2,3])
data.append(4)

Run this code, you will get the result:

Why does this attribute error occur?

Because there is no numpy.ndarray.append() funtion in numpy.ndarray.

How to fix this error?

We can use numpy.append() function.

numpy.append(arr, values, axis=None)

This function will append values to the end of an array.

As to example above, we can modify it to be:

import numpy as np

data = np.array([1,2,3])
datax = np.append(data, 4)
print(data)
print(datax)

Run this code, you will get the result as:

[1 2 3]
[1 2 3 4]

From the result we can find: The original numpy.ndarray data is not changed, numpy.append() function will return a new numpy.ndarray.

You will find this error is fixed.