Pandas DataFrame - count() function

The Pandas DataFrame - count() function is used to count non-NA cells for each column or row. The values None, NaN, NaT, and optionally pandas.inf (depending on pandas.options.mode.use_inf_as_na) are considered NA.

Syntax

DataFrame.count(axis=0, level=None, numeric_only=False)

Parameters

`axis`	`Optional.` Specify {0 or 'index', 1 or 'columns'}. If 0 or 'index' counts are generated for each column. If 1 or 'columns' counts are generated for each row. Default: 0
`level`	`Optional.` Specify level (int or str). If the axis is a MultiIndex (hierarchical), count along a particular level, collapsing into a DataFrame. A str specifies the level name.
`numeric_only`	`Optional.` Specify True to include only float, int or boolean data. Default: False

Return Value

Returns a Series of count of non-NA/null entries for each column/row. If level is specified DataFrame is returned.

Example: Using count() column-wise on whole DataFrame

In the below example, a DataFrame info is created. The DataFrame count() function is used to get the count of each column which only includes only non-NA values.

import pandas as pd
import numpy as np

info = pd.DataFrame({
	"Person": ["John", "Mary", "Jo", "Sam"],
	"Age": [25, 24, 30, 28],
	"Bonus": ["10K", np.nan, "10K", "9K"]
})

print(info)
print(info.count())

The output of the above code will be:

   Age Bonus Person
0   25   10K   John
1   24   NaN   Mary
2   30   10K     Jo
3   28    9K    Sam

Age       4
Bonus     3
Person    4
dtype: int64

Example: Using count() row-wise on whole DataFrame

To get the row-wise count, the axis parameter can set to 1.

import pandas as pd
import numpy as np

info = pd.DataFrame({
	"Person": ["John", "Mary", "Jo", "Sam"],
	"Age": [25, 24, 30, 28],
	"Bonus": ["10K", np.nan, "10K", "9K"]
})

print(info)
print(info.count(axis=1))

The output of the above code will be:

   Age Bonus Person
0   25   10K   John
1   24   NaN   Mary
2   30   10K     Jo
3   28    9K    Sam

0    3
1    2
2    3
3    3
dtype: int64

Example: Using count() on selected column

Instead of whole data frame, the count() function can be applied on selected columns. Consider the following example.

import pandas as pd
import numpy as np

info = pd.DataFrame({
	"Person": ["John", "Mary", "Jo", "Sam"],
	"Age": [25, 24, 30, 28],
	"Bonus": ["10K", np.nan, "10K", "9K"]
})

print(info)

#count on single column
print("\ncount on Person returns:")
print(info['Person'].count())

#count on multiple columns
print("\ncount on Person and Bonus returns:")
print(info[['Person', 'Bonus']].count())

The output of the above code will be:

   Age Bonus Person
0   25   10K   John
1   24   NaN   Mary
2   30   10K     Jo
3   28    9K    Sam

count on Person returns:
4

count on Person and Bonus returns:
Person    4
Bonus     3
dtype: int64

Example: Using count() with level parameter

The below example shows how to create one level of a MultiIndex.

import pandas as pd
import numpy as np

info = pd.DataFrame({
	"Person": ["John", "Mary", "Jo", "Sam"],
	"Age": [25, 24, 30, 28],
	"Bonus": ["10K", np.nan, "10K", "9K"]
})

print(info)

#count with level parameter
print(info.set_index(['Person', 'Bonus']).count(level='Person'))

The output of the above code will be:

   Age Bonus Person
0   25   10K   John
1   24   NaN   Mary
2   30   10K     Jo
3   28    9K    Sam

        Age
Person     
Jo        1
John      1
Mary      1
Sam       1

❮ Pandas DataFrame - Functions