Python is a great language for doing data analysis, primarily because of the fantastic ecosystem of data-centric python packages. Pandas is one of those packages and makes importing and analyzing data much easier.
Pandas dataframe.first_valid_index() function returns index for first non-NA/null value in the dataframe. In the case of Pandas Series, the first non-NA/null index is returned. In the case of pandas Dataframe, that index is returned which has even a single non-NA/null value.
Note : If all elements are non-NA/null, returns None. Also returns None for empty DataFrame
Syntax: DataFrame.first_valid_index()
Returns : scalar : type of index
Example #1: Use first_valid_index() function to find the first non-NA/null index in the dataframe.
# importing pandas as pd import pandas as pd # Creating the dataframe df = pd.DataFrame({"A":[None, None, 2, 4, 5], "B":[5, None, None, 44, 2], "C":[None, None, None, 1, 5]}) # Print the dataframe df |
Now apply the first_valid_index() function.
# applying first_valid_index() function df.first_valid_index() |
Output :
Notice, there is non-Na value in the second column of the first row. so the output is 0, indicating that 0th index contain a non-NA value.
Example #2: Use first_valid_index() function to find the first non-NA/null index in the dataframe.
# importing pandas as pd import pandas as pd # Creating the dataframe df = pd.DataFrame({"A":[None, None, 2, 4, 5], "B":[None, None, None, 44, 2], "C":[None, None, None, 1, 5]}) # applying first_valid_index() function df.first_valid_index() |
Output :
As we can see in the dataframe, the first two rows are having only NA values. so, the output is 2
Example #3: Use first_valid_index() function to find the first non-NA/null index in a series.
# importing pandas as pd import pandas as pd # Creating the series ser = pd.Series([None, None, "sam", "alex", "sophia", None]) # Print the series ser |
Now apply the first_valid_index() function.
# applying first_valid_index() function ser.first_valid_index() |
Output :
Output is 2 because 0th and 1st indexes are having null value.
