convert columns to uppercase or lowercase in pandas | str.lower(), str.upper() & map in pandas

In this pandas tutorial, we will discuss different ways to:

• convert columns to uppercase pandas,
• convert columns to lowercase pandas,
• str.lower() pandas & str.upper() pandas,
• map in pandas, 

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Here we will convert columns to uppercase or lowercase in pandas using str.lower() pandas, str.upper() pandas & map in pandas. But first lets prepare a dataframe on which we will work to show these conversions.

 

Pandas DataFrame is a two dimensional data structure that will store data in two dimensional format. One dimension refers to a row and second dimension refers to a column. So It will store the data in rows and columns.

 

We can create this DataFrame using DataFrame() method. But this is available in pandas module, so we have to import pandas module.

Syntax:

pandas.DataFrame(data)

Where, data is the input dataframe, The data can be a dictionary that stores list of values with specified key

 

Example: Create DataFrame

In this example, we will create dataframe with 4 rows and 4 columns with college data and assign indices through index parameter.

import pandas as pd

#create dataframe from the college data
data= pd.DataFrame({'college_id':['c-001','c-021','c-002','c-004'],

                    'college_name':["vignan university","vvit","RVR - JC","Andhra University"],

                   "college_address":["guntur","guntur","guntur","guntur"],

                    "Total Staff":['1200','3422','5644','670']

                   },index=['one','two','three','four'])

#display the dataframe
print(data)

Output: DataFrame is created below

      college_id       college_name college_address Total Staff
one        c-001  vignan university          guntur        1200
two        c-021               vvit          guntur        3422
three      c-002           RVR - JC          guntur        5644
four       c-004  Andhra University          guntur         670

Now we are going to use above dataframe to convert columns to lowercase pandas and convert columns to uppercase pandas.

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Method 1 - Using str.upper() & str.lower()

We can use str.upper() pandas to convert dataframe columns to upper case and str.lower() pandas to convert dataframe columns to lower case.

 

str.upper() pandas → convert columns to uppercase pandas.
str.lower() pandas → convert columns to lowercase pandas.

This method will take dataframe columns through columns method and then convert to lower/upper case.

Syntax:

dataframe.columns.str.upper()
dataframe.columns.str.lower()

Example: convert column to uppercase and lowercase in pandas

In this example, we will display the dataframe columns by converting the column names into uppercase and then to lowercase.

import pandas as pd
from tabulate import tabulate

#create dataframe from the college data
data= pd.DataFrame({'college_id':['c-001','c-021','c-002','c-004'],

                    'college_name':["vignan university","vvit","RVR - JC","Andhra University"],

                   "college_address":["guntur","guntur","guntur","guntur"],

                    "Total Staff":['1200','3422','5644','670']

                   },index=['one','two','three','four'])


# convert columns to upper case
print(data.columns.str.upper())

# convert columns to lower case
print(data.columns.str.lower())

Output: Here first code convert columns to uppercase pandas and then convert columns to lowercase pandas.

Index(['COLLEGE_ID', 'COLLEGE_NAME', 'COLLEGE_ADDRESS', 'TOTAL STAFF'], dtype='object')
Index(['college_id', 'college_name', 'college_address', 'total staff'], dtype='object')

From the above code, all the column names are converted to upper case using str.upper() and into lower case by using str.lower().

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Method 2 - Using map in pandas

We can use map in pandas to convert dataframe columns to upper case with str.upper parameter and  convert dataframe columns to lower case with str.lower parameter.

Syntax:

dataframe.columns = map(str.lower, dataframe.columns)

map in pandas method will take two parameters.

1. str.upper/str.lower - To convert the dataframe to upper/lower case
2. columns - to take dataframe columns

Example: map pandas example

In this map pandas example, we will display the dataframe columns by converting the column names into uppercase and lowercase.

import pandas as pd
from tabulate import tabulate

#create dataframe from the college data
data= pd.DataFrame({'college_id':['c-001','c-021','c-002','c-004'],

                    'college_name':["vignan university","vvit","RVR - JC","Andhra University"],

                   "college_address":["guntur","guntur","guntur","guntur"],

                    "Total Staff":['1200','3422','5644','670']

                   },index=['one','two','three','four'])


# convert columns to upper case
data.columns=map(str.upper, data.columns)

#display the columns
print(data.columns)

# convert columns to lower case
data.columns = map(str.lower, data.columns)

#display the columns
print(data.columns)

Output: Here first code convert columns to uppercase pandas and then convert columns to lowercase pandas.

Index(['COLLEGE_ID', 'COLLEGE_NAME', 'COLLEGE_ADDRESS', 'TOTAL STAFF'], dtype='object')
Index(['college_id', 'college_name', 'college_address', 'total staff'], dtype='object')

From the above code, all the column names are converted to upper case using str.upper() and into lower case by using str.lower() through map() in pandas function.