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Get columns from Pandas DataFrame | using columns, values, info, sorted methods

Get columns from Pandas DataFrame | using columns, values, info, sorted methods


In this chapter of pandas tutorial, we will discuss:

  • create dataframe in pandas,
  • get column names from pandas dataframe using columns method,
  • how to get columns from pandas dataframe using values on columns,
  • get columns from pandas dataframe using info(),
  • how to get sorted column in pandas,

Create DataFrame

DataFrame is a 2 dimensional data structure that stores data in 2 dimensional format. One dimension refers to a row and second dimension refers to a column. So it will store data in rows and columns.

 

We can create 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

 

Examplecreate dataframe pandas

In this example, we will create dataframe in pandas with 4 rows and 4 columns with college data

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]

                   })

#display the dataframe
print(data)

Output: Below dataframe is created

  college_id       college_name college_address  Total Staff

0      c-001  vignan university          guntur         1200

1      c-021               vvit          guntur         3422

2      c-002           RVR - JC          guntur         5644

3      c-004  Andhra University          guntur          670

Lets start to get columns from pandas dataframe. We will see different methods to do that task.


Method 1  - get columns from pandas dataframe using columns method

This columns is used to return or get columns from pandas dataframe in a list. It will also return the column datatype i.e object along with column name.

Syntax:

dataframe.columns

where, dataframe is the input dataframe

 

Exampleget column names from pandas dataframe using columns method is shown in below code snippet

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]

                   })



#display the columns in the dataframe

print(data.columns)

 

Output: We get column names from pandas dataframe below

Index(['college_id', 'college_name', 'college_address', 'Total Staff'], dtype='object')

Lets see another method to get column names from pandas dataframe.


Method 2 : get columns from pandas dataframe using columns.values

This columns.values is used to return the column names in a list without datatype.

Syntax:

dataframe.columns.values

where, dataframe is the input dataframe

 

Exampleextract column names from pandas dataframe using values

In this example, we are using shape function to return number of rows and columns in a tuple from the dataframe.

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]

                   })

#display the columns in the dataframe
print(data.columns.values)

Output: we successfully extract column names from pandas dataframe

['college_id' 'college_name' 'college_address' 'Total Staff']

Lets see another method to get columns from pandas dataframe.


Method 3 : get columns from pandas dataframe using sorted() function

This sorted() function is used to return the column names in a list without datatype in sorted order.

Syntax:

sorted(dataframe)

where, dataframe is the input dataframe

 

Example: Lets see how to get sorted column in pandas from below snippet:

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]

                   })

#display the columns in the dataframe

print(sorted(data))

Output:

['Total Staff', 'college_address', 'college_id', 'college_name']

You can see the sorting is done on columns.


Method 4 : get columns from pandas dataframe using info() function

This info() method will return the information about column. The information includes:

  • column names with associated datatypes and
  • count of Not Null values

Syntax:

dataframe.info()

where, dataframe is the input dataframe

 

Example: Lets get get columns from pandas dataframe with all information

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]

                   })



#display the columns in the dataframe

print(data.info())

Output: We get columns from pandas dataframe as below

<class 'pandas.core.frame.DataFrame'>

RangeIndex: 4 entries, 0 to 3

Data columns (total 4 columns):

 #   Column           Non-Null Count  Dtype

---  ------           --------------  -----

 0   college_id       4 non-null      object

 1   college_name     4 non-null      object

 2   college_address  4 non-null      object

 3   Total Staff      4 non-null      int64

dtypes: int64(1), object(3)

memory usage: 256.0+ bytes

None

Thus we get other details related to columns as well using info().


Conclusion

In this article, we first create dataframe in pandas and get columns from pandas dataframe explained in four ways - columns, values, sorted, info.

 


Pandas

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About the Author
Gottumukkala Sravan Kumar 171FA07058
B.Tech (Hon's) - IT from Vignan's University. Published 800+ Technical Articles on Python, R, Java, C#, LISP, PHP - MySQL and Machine Learning
Page Views :    Published Date : Feb 24,2022  
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