# Remove items in Array that are not in Another Array in Python

This tutorial will discuss about unique ways to remove elements from array that are not in another array – Python.

Suppose we have two NumPy Arrays,

```mainArray = np.array([14, 23, 30, 41, 53])
otherArray = np.array([23, 41])
```

Now we want to remove only those elements from the `mainArray` which are not present in the `otherArray`. Basically we want to keep the common values and delete all the or different values from the `mainArray`.

We will create a boolean mask, equal to the size of the `mainArray` using the `numpy.isin()` function. In which we will pass both the arrays as arguments.

```# Create a boolean mask equal to the size of mainArray
# Each True value in mask denotes that the corresponding
# value from mainArray is present in otherArray
```

It will return a boolean array, where each True value denotes at the corresponding value in `mainArray`is present in the `otherArray`. Then using the mask we will select only those values from the `mainArray` where this boolean sequence contains True value.

```# Use the mask to select only those values from mainArray
# where mask contains the True value at respective place
```

Basically we selected only the elements from mainArray which were present in the `otherArray`.

Let’s see the complete example,

```import numpy as np

# Create two NumPy Arrays
mainArray = np.array([14, 23, 30, 41, 53])
otherArray = np.array([23, 41])

# Create a boolean mask equal to the size of mainArray
# Each True value in mask denotes that the corresponding
# value from mainArray is present in otherArray

# Use the mask to select only those values from mainArray
# where mask contains the True value at respective place

# Print the numpy array
print(mainArray)
```

Output

```[23 41]

```

## Summary

We learned how to Remove Elements From a NumPy Array that are not present in Another NumPy Array in Python.

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