How to Get the Row Count of a Pandas DataFrame

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Asad Riaz Feb 02, 2024
Pandas Pandas DataFrame Row
  1. .shape Method to Get Row Count of DataFrame
  2. .len(DataFrame.index) as the Fastest Method to Get Row Count in Pandas
  3. dataframe.apply() to Count Rows That Satisfy a Condition in Pandas
How to Get the Row Count of a Pandas DataFrame

We will introduce how to get the row count of a Pandas DataFrame, with different methods like shape and len(DataFrame.index). They have notable performance differences and the len(DataFrame.index) method is the fastest.

We also look at how we can use dataframe.apply() to get how many elements of rows satisfies a condition or not.

.shape Method to Get Row Count of DataFrame

Suppose df is our DataFrame , to calculate row count,

# python 3.x
import pandas as pd
import numpy as np

df = pd.DataFrame(np.arange(15).reshape(3, 5))
print(df)
print("Row count is:", df.shape[0])

Output:

    0   1   2   3   4
0   0   1   2   3   4
1   5   6   7   8   9
2  10  11  12  13  14
Row count is: 3

For columns count, we can use df.shape[1].

.len(DataFrame.index) as the Fastest Method to Get Row Count in Pandas

We can calculate the row count in the DataFrame by getting the index row’s length.

# python 3.x
import pandas as pd
import numpy as np

df = pd.DataFrame(np.arange(15).reshape(3, 5))
print(df)
print("Row count is:", len(df.index))

Output:

    0   1   2   3   4
0   0   1   2   3   4
1   5   6   7   8   9
2  10  11  12  13  14
Row count is: 3

We can also pass df.axes[0] instead of df.index:

# python 3.x
import pandas as pd
import numpy as np

df = pd.DataFrame(np.arange(15).reshape(3, 5))
print(df)
print("Row count is:", len(df.axes[0]))

Output:

    0   1   2   3   4
0   0   1   2   3   4
1   5   6   7   8   9
2  10  11  12  13  14
Row count is: 3

For columns’ count we can use df.axes[1].

dataframe.apply() to Count Rows That Satisfy a Condition in Pandas

By counting the number of True in the returned result of dataframe.apply(), we can get the count of rows in DataFrame that satisfies the condition.

# python 3.x
import pandas as pd
import numpy as np

df = pd.DataFrame(np.arange(15).reshape(3, 5))
counterFunc = df.apply(lambda x: True if x[1] > 3 else False, axis=1)
numOfRows = len(counterFunc[counterFunc == True].index)
print(df)
print("Row count > 3 in column[1]is:", numOfRows)

Output:

    0   1   2   3   4
0   0   1   2   3   4
1   5   6   7   8   9
2  10  11  12  13  14
Row count > 3 in column[1]is: 2

We get the count of rows whose value in column[1] is greater than 3.

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