peta vs berlaku panda
difference between map and apply
map is defined on Series ONLY
applymap is defined on DataFrames ONLY
apply is defined on BOTH
map is meant for mapping values from one domain to another,
so is optimised for performance (e.g., df['A'].map({1:'a', 2:'b', 3:'c'}))
apply is for applying any function that cannot be vectorised
(e.g., df['sentences'].apply(nltk.sent_tokenize)
coder