Setting Column as Index in Pandas Dataframe
Usually, in Pandas Dataframe, we use the serial number from 0 to the length of the object as the index by default. We can also use a column in the DataFrame as its index. For this, we can use the ones provided in pandas set_index()or specify the column as the index when importing the DataFrame from Excel or CSV file.
set_index()Specifying columns as indexes in a Pandas DataFrame using
set_index()Can be applied to a list, sequence or DataFrame to change their index. For DataFrame, set_index()it is also possible to use multiple columns as their index.
example:
import pandas as pd
import numpy as np
colnames = ["Name", "Time", "Course"]
df = pd.DataFrame(
[["Jay", 10, "B.Tech"], ["Raj", 12, "BBA"], ["Jack", 11, "B.Sc"]], columns=colnames
)
print(df)
Output:
Name Time Course
0 Jay 10 B.Tech
1 Raj 12 BBA
2 Jack 11 B.Sc
The syntax for using a column as an index is:
dataframe.set_index(Column_name, inplace=True)
Use set_index()a column as an index.
import pandas as pd
import numpy as np
colnames = ["Name", "Time", "Course"]
df = pd.DataFrame(
[["Jay", 10, "B.Tech"], ["Raj", 12, "BBA"], ["Jack", 11, "B.Sc"]], columns=colnames
)
df.set_index("Name", inplace=True)
print(df)
Output:
Time Course
Name
Jay 10 B.Tech
Raj 12 BBA
Jack 11 B.Sc
To use multiple columns as indexes:
import pandas as pd
import numpy as np
colnames = ["Name", "Time", "Course"]
df = pd.DataFrame(
[["Jay", 10, "B.Tech"], ["Raj", 12, "BBA"], ["Jack", 11, "B.Sc"]], columns=colnames
)
df.set_index(["Name", "Course"], inplace=True)
print(df)
Output:
Time
Name Course
Jay B.Tech 10
Raj BBA 12
Jack B.Sc 11
Use the index parameter in read_excelor to index columns in a Pandas DataFrameread_csvindex_col
When reading a DataFrame from an excel or CSV file, we can specify the columns we want as the index of the DataFrame.
example:
import pandas as pd
import numpy as np
df = pd.read_excel("data.xlsx", index_col=2)
print(df)
Output:
Name Time
Course
B.Tech Mark 12
BBA Jack 10
B.Sc Jay 11
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