What's the difference of 'loc, iloc, iat' in python?

loc: only work on index
iloc: work on position
ix: You can get data from dataframe without it being in the index
at: get scalar values. It's a very fast loc
iat: Get scalar values. It's a very fast iloc

Reference:

https://stackoverflow.com/questions/28757389/pandas-loc-vs-iloc-vs-ix-vs-at-vs-iat