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convert column to float pandas | astype pandas float

convert column to float pandas | astype pandas float


In this pandas tutorial, we will discuss about:

  • print data type in pandas,
  • convert column to float pandas,
  • astype pandas float

Lets first go through the concept of dataframe.

 

DataFrame in pandas is an 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 able to 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 and print type of dataframe

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

 

We can get the dataframe datatypes using dtypes method.

Syntax:

dataframe.dtypes

In the below code we create and print data type in pandas 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']

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

#display the dataframe
print(data)

# display the datatypes
print(data.dtypes)

Outputprint data type in pandas result is 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
college_id         object
college_name       object
college_address    object
Total Staff        object
dtype: object

Now we will use above dataframe to convert column to float in pandas.


Convert column to float in pandas

Lets see different methods to convert column to float in pandas.

 

Method 1convert column to float in pandas using astype()

This astype pandas method will take dataframe column as input and convert the data type to float.

We can convert to float by specifying a keyword called 'float'.

Syntax:

dataframe['column'].astype(float)

where,

1. dataframe is the input dataframe

2. column is the name of the column in which the datatype to be converted.

 

Note - In pandas DataFrame, the string type column will be considered as an object.

Exampleconvert column to float in pandas example

In this convert column to float in pandas example, we will convert Total Staff column to float type

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'])

# convert Total Staff column to float type
data['Total Staff']=data['Total Staff'].astype(float)

# display the datatypes
print(data.dtypes)

# display the dataframe
print(data)

Outputconvert column to float in pandas for column total staff

college_id          object
college_name        object
college_address     object
Total Staff        float64
dtype: object
      college_id       college_name college_address  Total Staff
one        c-001  vignan university          guntur       1200.0
two        c-021               vvit          guntur       3422.0
three      c-002           RVR - JC          guntur       5644.0
four       c-004  Andhra University          guntur        670.0

From the output we observed that  data type of Total Staff column is object before  and now it is converted to Float type and we displayed the entire dataframe.


Method 2convert column to float pandas using astype() with dictionary

This astype pandas method with dictionary will take dataframe column as input and convert the data type to float.

 

We can convert to float by specifying a keyword called 'float'.

 

astype() will take column name inside a dictionary, such that key will be the column name and value will be the float keyword.

Syntax:

dataframe.astype({"column":float})

where,

1. dataframe is the input dataframe

2. column is the name of the column in which the datatype to be converted.

 

Note - In pandas DataFrame, the string type column will be considered as an object.

Exampleconvert column to float in pandas example

In this convert column to float in pandas example, we will convert Total Staff column to float type

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'])

# convert Total Staff column to float type
data = data.astype({"Total Staff": float})

# display the datatypes
print(data.dtypes)

Output: result for convert column to float in pandas on total staff column is given below

college_id          object
college_name        object
college_address     object
Total Staff        float64
dtype: object

From the output we observed that  data type of Total Staff column is object before  and now it is converted to Float type.


Method 3 : convert column to float pandas using astype() by specifying the type

This astype pandas method will take dataframe column as input and convert the data type to float.

 

We can convert to float by specifying a keyword called 'float'. But we have to specify the old datatype of the column to be converted.

Syntax:

dataframe['column'].astype(old_datatype).astype(float)

where,

1. dataframe is the input dataframe

2. column is the name of the column in which the datatype to be converted.

3. old_datatype is the datatype of the column (like str,int etc)

 

Note - In pandas DataFrame, the string type column will be considered as an object.

Exampleconvert column to float in pandas example

In this convert column to float pandas example, we will convert Total Staff column to float type

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'])

# convert Total Staff column to float type
data['Total Staff'] = data['Total Staff'].astype(str).astype(float)

# display the datatypes
print(data.dtypes)

Outputconvert column to float pandas result for total staff column

college_id         object
college_name       object
college_address    object
Total Staff       float64
dtype: object

From the output we observed that  data type of Total Staff column is object before  and now it is converted to Float type.

 

In this way we can convert column to float in pandas.


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
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