How to replace a column with a series in Polars
The replace_column() function is a method in the Polars’s DataFrame that replaces an entire column at a specified index with a new Series. This operation is performed in place, meaning it modifies the original DataFrame directly.
Syntax
The syntax of the replace_column() function is given below:
DataFrame.replace_column(index: int , column: Series)
Parameters
index: It specifies the index of the column that will be replaced. It refers to the position of the column within the DataFrame.column: It represents the Series that will replace the existing column at the specified index.
Code
To utilize the functionality of replace_column(), we’ll create a DataFrame containing three columns and a new series. Let’s explore how we can replace the values of the column at index 0 with the new series in the provided code example.
import polars as pldf = pl.DataFrame({"A": [1, 2, 3],"B": [4, 5, 6],"C": [7, 8, 9]})# Create a new Seriesnew_series = pl.Series("D", [10, 20, 30])# Replace the column at index 0 ("A") with the new Seriesdf.replace_column(0, new_series)print(df)
Explanation
Lines 3–7: We create a DataFrame named
dfwith three columnsA,B, andC. The DataFrame is initialized with a dictionary where keys are column names, and values are lists representing column values.Line 10: We create a new
Seriesnamednew_serieswith a column name (D) and values ([10, 20, 30]).Line 13: The
replace_columnmethod is called on the DataFramedfto replace the values in the column at index 0 (A) with the values from thenew_seriesSeries. This operation is performed in place.Line 14: We print the
dfDataFrame after the replacement operation. The output will show the modified DataFrame with the new values in the specified column.
Wrap up
The replace_column method offers a powerful, in-place solution for updating entire columns at specified indexes in a DataFrame. Together, these functions empower data professionals to efficiently address data quality issues, standardize information, and seamlessly manage and transform tabular data.
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