How to use the series.isin() method to check values in a series?

The Pandas series.isin() function is used to check whether the requested values are contained in the given Series object or not. It will return a boolean series object showing whether each element in the series matches the elements in the past sequence to the isin() method.

The boolean value True represents the matched elements in series that are specified in the input sequence of the isin() method, and not matched elements are represented with False.

The isin() method expects only a sequence of values and not a Series of sequences or a direct value. This means, it allows vectorization on keys but not on values.

It will raise TypeError, if any other data passed, only list-like objects are allowed to be passed to isin() method.

Example 1

We will use the Series.isin() function to check whether the passed values are available in the series object or not.

# importing pandas package
import pandas as pd

#creating pandas Series
series = pd.Series([7, 2, 6, 2, 5, 4, 1, 2, 3, 8])

print(series)

# Apply isin() function to check for the specified values
result = series.isin([2])

print("Output:")
print(result)

Output

The output is as follows −

0    7
1    2
2    6
3    2
4    5
5    4
6    1
7    2
8    3
9    8
dtype: int64

Output:
0    False
1    True
2    False
3    True
4    False
5    False
6    False
7    True
8    False
9    False
dtype: bool

As we can see in the output block, the Series.isin() method has returned a new series object with boolean values. True indicates the values at that particular instance are matched to the given sequence. False indicates Reverse.

Example 2

Here we will see how to check multiple values at a time by passing a list of values to the isin() method.

# importing pandas package
import pandas as pd

#creating pandas Series
series = pd.Series(['A', 'B', 'C', 'A', 'D', 'E', 'B'], index=[1, 2, 3, 4, 5, 6, 7])

print("Series object:")
print(series)

# Apply isin() function to check for the specified values
result = series.isin(['A', 'B'])

print("Output:")
print(result)

Output

The output is given below −

Series object:
1    A
2    B
3    C
4    A
5    D
6    E
7    B
dtype: object

Output:
1    True
2    True
3    False
4    True
5    False
6    False
7    True
dtype: bool

In the above output block, We can observe that the values at index 1, 2, 4, and 7 are matched to the given sequence of values, while the remaining are not.

Gireesha Devara

Updated on 08-Mar-2022 09:15:51

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