# How to add a column to a NumPy array in Python

Hello folks, in this tutorial we are going to learn how to add a column to a NumPy array in Python language. Two methods are discussed below.

It is obvious that we need to import NumPy library before we begin.

To know more about NumPy arrays,refer this

## Using append or insert to add a column to a NumPy array in Python

Method-1 (Using append method):

Append method requires three parameters:

1. Original array – The array to which we wanted to add a column
2. New Values – The values of the column we wanted to add
3. Axis – The axis by which we wanted to append, this is always 1 in this case

Let’s look into an example

arr = [[1,2,3] , [4,5,6] , [7,8,9]]

newcolumn = [[99],[100],[101]]

```import numpy as np
original = [[1,2,3],[4,5,6],[7,8,9]]
arr = np.array(original)
print("The original array is :")
print(arr)
print("--------------------------")
newcolumn = [[99],[100],[101]]
newarray=np.append(arr,newcolumn,axis=1)
print(newarray)```

Output:

```The original array is :

[[1 2 3]

[4 5 6]

[7 8 9]]

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

[[ 1 2 3 99]

[ 4 5 6 100]

[ 7 8 9 101]]

```

#### Method – 2 (Using insert method):

Insert method helps in adding the column at any position as per the requirement. It requires 4 parameters. They are:

1. Original array – The array to which we wanted to add a column
2. Index – The position where we want to add a column
3. Values – Values of the new column
4. Axis-The axis by which we wanted to append, this is always 1 in this case

Example:

arr = [[1,2,3] , [4,5,6] , [7,8,9]]

newcolumn = [99,100,101]

To add the newcolumn in the second position, we need to assign 1 for index parameter

index = 1

```import numpy as np
original = [[1,2,3],[4,5,6],[7,8,9]]
arr = np.array(original)
print("The original array is :")
print(arr)
print("--------------------------")
newcolumn = [99,100,101]
index=1
newarray=np.insert(arr,index,newcolumn,axis=1)
print(newarray)
```

Output:

```The original array is :
[[1 2 3]
[4 5 6]
[7 8 9]]
--------------------------