Hands-On Data Analysis with Pandas

The long data format

We can look at the top six rows of the long format data in long_df to see the differences between wide format and long format data:

>>> long_df.head(6)

Long format data will have a row for each observation of a variable; this means that, if we have three variables being measured daily, we have three rows for each day we record observations. The long format setup can be achieved by turning the variable column names into a column where the data is the variable name and putting their values in a separate values column:

date	datatype	value
0	2018-10-01	TMAX	21.1
1	2018-10-01	TMIN	8.9
2	2018-10-01	TOBS	13.9
3	2018-10-02	TMAX	23.9
4	2018-10-02	TMIN	13.9
5	2018-10-02	TOBS	17.2

Notice how in the preceding ...