# How to Get the First Column of a Numpy Array?

Numpy arrays are very versatile when it comes to manipulating and extracting values. In this tutorial, we will look at how to get the first column of a two-dimensional Numpy array with the help of some examples.

## Steps to get the first column of a Numpy Array

Let’s look at a step-by-step example of how to extract the first column from a two-dimensional Numpy array.

### Step 1 – Create a 2D Numpy array

First, we will create a 2D Numpy array that we will use throughout this tutorial.

```import numpy as np

# create 2D Numpy array
ar = np.array([
[1, 2, 3],
[4, 5, 6],
[7, 8, 9]
])
# display the array
print(ar)```

Output:

```[[1 2 3]
[4 5 6]
[7 8 9]]```

Here, we used the `numpy.array()` function to create a two-dimensional Numpy array having three rows and three columns.

You can see that the first column of the above array contains the values 1, 4, and 7

### Step 2 – Slice the array to get the first column

You can use slicing to extract the first column of a Numpy array. The idea is to slice the original array for all the rows and just the first column (which has a column index of 0).

For example, to get the first column of the array `ar` use the syntax `ar[:, 0]`.

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Let’s get the first column of the array created above.

```# get the first column
ar[:, 0]```

Output:

`array([1, 4, 7])`

We get a Numpy array of the values in the first column of our original array (`ar`). Note that the resulting array, here, is one-dimensional.

`ar[:, 0].shape`

Output:

`(3,)`

If you instead want the first column as a Numpy array with shape `(3, 1)` (like a column vector) use the following syntax –

```# get the first column
ar[:, [0]]```

Output:

```array([[1],
[4],
[7]])```

We get the first column from the original array as a separate column (sort of like a column vector). Let’s see its shape.

`ar[:, [0]].shape`

Output:

`(3, 1)`

You can see that the resulting array is of shape `(3, 1)`

## Summary

In this tutorial, we looked at how to extract the first column of a two-dimensional Numpy array. The following is a short summary of the steps mentioned in this tutorial.

1. Create a 2D Numpy array (skip this step if you already have an array to operate on).
2. Use slicing to get the first column of the array –
• If you want the values in the first column as a simple one-dimensional array, use the syntax `ar[:, 0]`.
• If you want the resulting values in a column vector (for example, with shape `(n, 1)` where n is the total number of rows), use the syntax `ar[: [0]]`.

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