Return the Index label if some condition is satisfied over a column in Pandas Dataframe

Given a Dataframe, return all those index labels for which some condition is satisfied over a specific column.

Solution #1: We can use simple indexing operation to select all those values in the column which satisfies the given condition.

# importing pandas as pd
import pandas as pd

# Create the dataframe
df = pd.DataFrame({'Date':['10/2/2011', '11/2/2011', '12/2/2011', '13/2/2011'],
                   'Product':['Umbrella', 'Matress', 'Badminton', 'Shuttle'],
                   'Last_Price':[1200, 1500, 1600, 352],
                   'Updated_Price':[1250, 1450, 1550, 400],
                   'Discount':[10, 10, 10, 10]})

# Create the indexes
df.index =['Item 1', 'Item 2', 'Item 3', 'Item 4']

# Print the dataframe
print(df)

Output :

Now, we want to find out the index labels of all items whose ‘Updated_Price’ is greater than 1000.

# Select all the rows which satisfies the criteria
# convert the collection of index labels to list.
Index_label = df[df['Updated Price']>1000].index.tolist()

# Print all the labels
print(Index_label)

Output :

As we can see in the output, the above operation has successfully evaluated all the values and has returned a list containing the index labels.

Solution #2: We can use Pandas Dataframe.query() function to select all the rows which satisfies some condition over a given column.

# importing pandas as pd
import pandas as pd

# Create the dataframe
df = pd.DataFrame({'Date':['10/2/2011', '11/2/2011', '12/2/2011', '13/2/2011'],
                   'Product':['Umbrella', 'Matress', 'Badminton', 'Shuttle'],
                   'Last_Price':[1200, 1500, 1600, 352],
                   'Updated_Price':[1250, 1450, 1550, 400],
                   'Discount':[10, 10, 10, 10]})

# Create the indexes
df.index =['Item 1', 'Item 2', 'Item 3', 'Item 4']

# Print the dataframe
print(df)

Output :

Now, we want to find out the index labels of all items whose ‘Updated_Price’ is greater than 1000.

# Select all the rows which satisfies the criteria
# convert the collection of index labels to list.
Index_label = df.query('Updated_Price > 1000').index.tolist()

# Print all the labels
print(Index_label)

Output :