Join()- join or concatenate string in pandas Python dataframe

join or concatenate string in pandas python – Join() function is used to join or concatenate two or more strings in pandas python with the specified separator. In this tutorial lets see

• How to join or concatenate two strings with specified separator
• how to concatenate or join the two string columns of dataframe in python.
• How to concatenate or join an integer and string column in python

Syntax for string join() function in python:

sequence — This is a sequence of the elements to be joined.

Example 1 – join or concatenate two strings

Simple string join is shown below

a= "python is"
b="My Favourite Language"
	
#join with space separator
print " ".join((a,b))


#join with : separator
print ": ".join((a,b))

so the output will be

Example 2 – concatenate or join an integer and string column in python:

Create dataframe:

##create dataframe

import pandas as pd
d = {'Quarters' : ['quarter1','quarter2','quarter3','quarter4'],
     'Revenue':[23400344.567,54363744.678,56789117.456,4132454.987]}
df=pd.DataFrame(d)
print df	

the dataframe will be

Join or concatenate columns of dataframe in python:

# join or concatenate two columns in pythons with space as separator

df['Quarters_revenue_concat1'] = df["Quarters"]+ " " + df["Revenue"].map(str)
print df

• Revenue column is type casted to string before concatenating

resultant dataframe  will have space separated concatenated column

# join or concatenate two columns in pythons with dash as separator

df['Quarters_revenue_concat1'] = df["Quarters"]+ "-" + df["Revenue"].map(str)
print df

resultant dataframe will have dash separated concatenated column

Example 3 on concatenation or join of two string columns in python dataframe:

Create dataframe:

##create dataframe

import pandas as pd
d = {'Quarters' : ['quarter1','quarter2','quarter3','quarter4'],
     'Alias' : ['q1','q2','q3','q4']}
df=pd.DataFrame(d)
print df

dataframe will be

# join or concatenate two string columns in python with apply function

df[' Quarters_Alias_concat'] = df[['Quarters', 'Alias']].apply(lambda x: '-'.join(x), axis=1)
print df

We will be using apply function to join two string columns of the dataframe so the resultant  dataframe will be