Pandas isin()

import pandas as pd

# create a sample DataFrame
data = {'A': [1, 2, 3, 4],
        'B': [5, 6, 7, 8]}

df = pd.DataFrame(data)

# select rows where DataFrame column 'A' is in the values list
result = df['A'].isin([2, 4])

# print the resulting boolean DataFrame
print(result)

'''
Output

0    False
1     True
2    False
3     True
Name: A, dtype: bool
'''

isin() Syntax

The syntax of the isin() method in Pandas is:

obj.isin(values)

isin() Argument

The isin() method takes the following argument:

• values - a set of values which can be a list, Series, or DataFrame.

isin() Return Value

The isin() method returns a boolean DataFrame (or Series) showing whether each element in the object is contained in the specified values.

Example 1: Using isin() with a Series

import pandas as pd

# create a sample Series
series_data = pd.Series([1, 2, 3, 4, 5])

# checking elements in Series that are in the provided list
result = series_data.isin([1, 3, 5])

# print the resulting boolean Series
print(result)

Output

0     True
1    False
2     True
3    False
4     True
dtype: bool

In this example, the isin() method checks each value in the Series against the provided list, resulting in a boolean Series.

Example 2: DataFrame with Multiple Columns

import pandas as pd

# create a sample DataFrame
data = {'A': [1, 2, 3],
        'B': [4, 5, 6]}
df = pd.DataFrame(data)

# specify values to check in each column
values = {'A': [1, 3], 'B': [5, 6]}

# check if DataFrame elements are present in the specified values
result = df.isin(values)

print(result)

Output

       A      B
0   True  False
1  False   True
2   True   True

Here, we provided a dictionary to the isin() method, containing values to check for each column in the DataFrame.

Example 3: Entire DataFrame Comparison

import pandas as pd

# create two sample DataFrames
data = {'A': [1, 2, 3],
        'B': [4, 5, 6]}
df1 = pd.DataFrame(data)

data2 = {'A': [1, 2],
         'B': [4, 5]}
df2 = pd.DataFrame(data2)

# check whether df1 contains elements of df2
result = df1.isin(df2)

print(result)

Output

      A     B
0  True  True
1  True  True
2 False False

In this case, we used isin() to check if elements of one DataFrame (df1) are present in another DataFrame (df2).