# 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.