Meaning and implementation of loc[~value]

Question

Watching this piece of code in the book:

def split_train_test_by_id(data, test_ratio, id_column, hash=hashlib.md5):
ids = data[id_column]
in_test_set = ids.apply(lambda id_: test_set_check(id_, test_ratio, hash))
return data.loc[~in_test_set], data.loc[in_test_set]

Never saw this loc[~<..>] before. Probably understanding the functionality, however want to be sure. Also is it working only in pandas or python in general?

https://www.programiz.com/python-programming/operators - It is a bitwise NOT — Joshua Nixon, May 14 '19 at 13:01
It works in general, but not when indexing lists (the example you give is NumPy.Pandas specific). Try ~0 in the Python prompt, and variants. — 9769953, May 14 '19 at 13:18
thanks, both comments as well as answer below helped a lot actually. Got it now — zzHQzz, May 20 '19 at 10:49

score 0 · Accepted Answer · answered May 14 '19 at 15:11

I saw some great comments above, but wanted to make sure that it's clear for a beginner. The ~ flips 1s to 0s and 0s to 1s. It is commonly used with pandas to signify not. In your example, ~in_test_set is similar to saying not in_test_set. The advantage to ~ is that it works with a set of values and is not limited to a single value. See the Python wiki on bitwise operators.

Meaning and implementation of loc[~*value*]

1 Answers1

Meaning and implementation of loc[~value]