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.
Allowed inputs are:
- 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)
.iloc will raise IndexError if a requested indexer is out-of-bounds, except slice indexers which allow out-of-bounds indexing (this conforms with python/numpy slice semantics).
See more at Selection by Position