How to access a single value in pandas Data Frame using the .at attribute?

PandasServer Side ProgrammingProgramming

The pandas DataFrame.at attribute is used to access a single value using the row and column labels. The “at” attribute takes a row and column labels data to get an element from a specified label position of the given DataFrame object.

It will return a single value based on the row and column label, and we can also upload a value in that particular position.

The .at attribute will raise a KeyError if the specified label is not available in the DataFrame.

Example 1

In this following example, we have created a Pandas DataFrame using a python dictionary. The column name is labeled by using the keys in the dictionary and the indexes are auto-generated values from 0 to n-1.

# importing pandas package
import pandas as pd

# create a Pandas DataFrame
df = pd.DataFrame({'A':[1, 2, 3],'B':[7, 8, 6],"C":[5, 6, 2]})

print("DataFrame:")
print(df)

# Access a single value from the DataFrame
result = df.at[0, 'B']
print("Output:",result)

Output

The output is given below −

DataFrame:
   A  B  C
0  1  7  5
1  2  8  6
2  3  6  2

Output: 7

We can see both initialized series object and output for at attribute in the above block. The .at attribute returns 7 for the following row/column pair df.at[0, 'B'].

Example 2

Now let’s update the value “100” in the position [2, 'B'] of the DataFrame object using the at attribute, 2 means the row index and “B” means column name.

# importing pandas package
import pandas as pd

# create a Pandas DataFrame
df = pd.DataFrame({'A':[1, 2, 3],'B':[7, 8, 6],"C":[5, 6, 2]})

print("DataFrame:")
print(df)

# by using .at attribute update a value
df.at[2, 'B'] = 100

print("Value 100 updated:")
print(df)

Output

The output is as follows −

DataFrame:
  A B C
0 1 7 5
1 2 8 6
2 3 6 2

Value 100 updated:
  A   B C
0 1   7 5
1 2   8 6
2 3 100 2

We have successfully updated the value “100” in the last row of the middle column (2, B), we can see the updated DataFrame object in the above output block.

raja
Updated on 08-Mar-2022 09:20:38

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