Purely integer-location based indexing for selection by position.
.iloc is primarily integer position based (from 0 to
length-1 of the axis), but may also be used with a boolean array.
An integer, e.g. 5.
A list or array of integers, e.g. [4, 3, 0].
A slice object with ints, e.g. 1:7.
A boolean array.
A callable function with one argument (the calling Series, DataFrame
or Panel) and that returns valid output for indexing (one of the above).
This is useful in method chains, when you don’t have a reference to the
calling object, but would like to base your selection on some value.
[4, 3, 0]