Pandas DataFrame first() Method
Example
Return the rows for the first 5 days:
    import pandas as pd
jan = pd.date_range(start='2021-01-01', 
    end='2021-01-31')
data = {
  "registered": [5, 4, 3, 4, 3, 5, 
    1, 6, 1, 9, 5, 3, 7, 2, 8, 4, 4, 6, 4, 3, 2, 5, 3, 4, 2, 6, 8, 5, 3, 4, 5]
    }
df = pd.DataFrame(data, index=jan)
print(df.first('5D'))
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Definition and Usage
The first() method returns the first n rows, 
based on the specified value.
The index have to be dates for this method to work as expected.
Syntax
  
    dataframe.first(offset)
  
Parameters
| Parameter | Description | 
|---|---|
| offset | Required. A String or a Date offset. Specifies the dates to return | 
Return Value
A DataFrame, with the specified rows.