Numerical Computing with Python

How to do it...

1. First, take note that the state names are in the index of the DataFrame. These states are correctly placed vertically and do not need to be restructured. It is the column names that are the problem. The stack method takes all of the column names and reshapes them to be vertical as a single index level:

>>> state_fruit.stack()Texas    Apple      12
         Orange     10
         Banana     40
Arizona  Apple       9
         Orange      7
         Banana     12
Florida  Apple       0
         Orange     14
         Banana    190
dtype: int64

2. Notice that we now have a Series with a MultiIndex. There are now two levels in the index. The original index has been pushed to the left to make room for the old column names. With this one command, we now essentially have tidy data. Each variable, state, fruit, and weight is vertical. ...