인프런 커뮤니티 질문&답변

데이터마님에 전처리100문제 훑어보고 있어요

람다식이 있어서 시험환경 문제1의 데이터로 응용해서 해보려니 안되네요 ㅠㅠ

그냥 딕셔너리 형태를 넣으면 되구요...

help에서는 딕셔너리 아니면 시리즈를 넣으라고 되어있는데 그래서 안되는건지...

a.cyl = a.cyl.astype('object')

dic = {

'4' : 'N',

'6' : 'a',

'8' : 'b'

}

a['newcyl'] =a.cyl.map(dic)

print(a.cyl)

a['newcyl'] =a.cyl.map(lambda x: dic[x])

> Makefile:6: recipe for target 'py3_run' failed

make: *** [py3_run] Error 1

Traceback (most recent call last):

File "/goorm/Main.out", line 18, in <module>

a['newcyl'] =a.cyl.map(lambda x: dic[x])

File "/usr/local/lib/python3.9/dist-packages/pandas/core/series.py", line 4237, in map

new_values = self._map_values(arg, na_action=na_action)

File "/usr/local/lib/python3.9/dist-packages/pandas/core/base.py", line 880, in mapvalues

new_values = map_f(values, mapper)

File "pandas/_libs/lib.pyx", line 2870, in pandas._libs.lib.map_infer

File "/goorm/Main.out", line 18, in <lambda>

a['newcyl'] =a.cyl.map(lambda x: dic[x])

KeyError: 6

help

map(arg, na_action=None) -> 'Series' method of pandas.core.series.Series instance

Map values of Series according to an input mapping or function.

Used for substituting each value in a Series with another value,

that may be derived from a function, a ``dict`` or

a :class:`Series`.

Parameters

----------

arg : function, collections.abc.Mapping subclass or Series

Mapping correspondence.

na_action : {None, 'ignore'}, default None

If 'ignore', propagate NaN values, without passing them to the

mapping correspondence.