# numpy.newaxis Method

This tutorial will discuss the `numpy.newaxis` method.

## the `numpy.newaxis` Method

The `numpy.newaxis` method is an alias for the `None`, which is used for array indexing in Python. The most straightforward use of the `numpy.newaxis` is to add a new dimension to a NumPy array in Python. For example, converting a 1D array into a 2D array, converting a 2D array into a 3D array, and so on. We can also convert a 1D array to either a row matrix or a column matrix with the `numpy.newaxis` in Python. The following code example shows us how to transform a 1D array into a row matrix with the `numpy.newaxis` in Python.

``````import numpy as np

array = np.array([1,2,3,4])
print(array.shape)

array = array[np.newaxis]
print(array.shape)
``````

Output:

``````(4,)
(1, 4)
``````

We transformed the 1D array `array` into a row matrix with the `np.newaxis` in the above code. We first created the 1D array `array` with the `np.array()` function. We then used the `[np.newaxis]` as the index of the `array` to return a row matrix. The following code example shows us how to transform a 1D array into a column matrix with the `numpy.newaxis`.

``````import numpy as np

array = np.array([1,2,3,4])
print(array.shape)

array = array[:,np.newaxis]
print(array.shape)
``````

Output:

``````(4,)
(4, 1)
``````

We transformed the 1D array `array` into a column matrix with the `np.newaxis` in the above code. We first created the 1D array `array` with the `np.array()` function. We then used the `[:, np.newaxis]` as the index of the `array` to return a column matrix.

As we have mentioned previously, the `numpy.newaxis` is an alias for `None`. So, we can also perform both operations discussed above with the `None` in place of the `numpy.newaxis`. The following code example shows us how to transform a 1D array into a row matrix with the `None` in Python.

``````import numpy as np

array = np.array([1,2,3,4])
print(array.shape)

array = array[None]
print(array.shape)
``````

Output:

``````(4,)
(1, 4)
``````

We transformed the 1D array `array` into a row matrix with the `None` in Python in the above code. We first created the 1D array `array` with the `np.array()` function. We then used the `[None]` as the index of the `array` to return a row matrix.

The following code example shows us how to transform a 1D array into a column matrix with the `None` in Python.

``````import numpy as np

array = np.array([1,2,3,4])
print(array.shape)

array = array[:, None]
print(array.shape)
``````

Output:

``````(4,)
(4, 1)
``````

We transformed the 1D array `array` into a column matrix with the `None` in Python in the above code. We first created the 1D array `array` with the `np.array()` function. We then used the `[:, None]` as the index of the `array` to return a column matrix.

In conclusion, both `numpy.newaxis`, and `None` are the same and can be used in array indexing and slicing.

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