Pandas DataFrame merge() Method

Example

Update the content of one DataFrame with the content from another DataFrame:

import pandas as pd

data1 = {
"name": ["Sally", "Mary", "John"],
"age": [50, 40, 30]
}

data2 = {
"name": ["Sally", "Peter", "Micky"],
"age": [77, 44, 22]
}

df1 = pd.DataFrame(data1)
df2 = pd.DataFrame(data2)

newdf = df1.merge(df2, how='right')

Try it Yourself »

Definition and Usage

The merge() method updates the content of two DataFrame by merging them together, using the specified method(s).

Use the parameters to control which values to keep and which to replace.

Syntax

dataframe.merge(right, how, on, left_on, right_on, left_index, right_index, sort, suffixes, copy, indicator, validate)

Parameters

All parameters except right, are keyword arguments.

Parameter	Value	Description
right		Required. A DataFrame, a Series to merge with
how	`'left' 'right' 'outer' 'inner' 'cross'`	Optional. Default 'inner'. Specifies how to merge
on	String List	Optional. Specifies in what level to do the merging
left_on	String List	Optional. Specifies in what level to do the merging on the DataFrame to the left
right_on	String List	Optional. Specifies in what level to do the merging on the DataFrame to the right
left_index	`True False`	Optional. Default False. Whether to use the index from the left DataFrame as join key or not
right_index	`True False`	Optional. Default False. Whether to use the index from the right DataFrame as join key or not
sort	`True False`	Optional. Default False. Specifies whether to sort the DataFrame by the join key or not
suffixes	List	Optional. Default '_x', '_y''. Specifies a list of strings to add for overlapping columns
copy	`True False`	Optional. Default True. Specifies whether to keep copies or not
indicator	`True False` String	Optional. Default False. Specifies whether to add a column in the DataFrame with information about the source of each row
validate	String	Optional. Checks if the mergin is of a specified type