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To retrieve the value of Val2 based on ID = 345, you can use the .loc function with the dataframe as the first argument and the index of the desired row (in this case, 2) as the second argument. This will return the value of Val2 associated with ID = 345, which is ‘C’.
You can use the query() function in pandas to extract the value in one column based on the value in another column.
This function uses the following basic syntax:
df.query("team=='A'")["points"]
This particular example will extract each value in the points column where the team column is equal to A.
The following examples show how to use this syntax in practice with the following pandas DataFrame:
import pandas as pd #create DataFrame df = pd.DataFrame({'team': ['A', 'A', 'A', 'A', 'B', 'B', 'B', 'B'], 'position': ['G', 'G', 'F', 'F', 'G', 'G', 'F', 'F'], 'points': [11, 28, 10, 26, 6, 25, 29, 12]}) #view DataFrame print(df) team position points 0 A G 11 1 A G 28 2 A F 10 3 A F 26 4 B G 6 5 B G 25 6 B F 29 7 B F 12
Example 1: Extract Column Values Based on One Condition Being Met
The following code shows how to extract each value in the points column where the value in the team column is equal to ‘A’:
#extract each value in points column where team is equal to 'A' df.query("team=='A'")["points"] 0 11 1 28 2 10 3 26 Name: points, dtype: int64
This function returns all four values in the points column where the corresponding value in the team column is equal to ‘A’.
Example 2: Extract Column Values Based on One of Several Conditions Being Met
The following code shows how to extract each value in the points column where the value in the team column is equal to ‘A’ or the value in the position column is equal to ‘G’:
#extract each value in points column where team is 'A' or position is 'G' df.query("team=='A' | position=='G'")["points"] 0 11 1 28 2 10 3 26 4 6 5 25 Name: points, dtype: int64
This function returns all six values in the points column where the corresponding value in the team column is equal to ‘A’ or the value in the position column is equal to ‘G’.
Example 3: Extract Column Values Based on Several Conditions Being Met
The following code shows how to extract each value in the points column where the value in the team column is equal to ‘A’ and the value in the position column is equal to ‘G’:
#extract each value in points column where team is 'A' and position is 'G' df.query("team=='A' & position=='G'")["points"] 0 11 1 28 Name: points, dtype: int64