python中的lambda解释

Question

I'm a newbie in Data Analytics. Can someone please explain the use of the lambda for counting x using lambda function.

specific_lambda=lambda x: set(['Adventure','Fantasy', 'Comedy','Drama']).issubset(x)
comic_movies=df[df.geners_arr.map(specific_lambda)]
comic_movies

count_lambda=lambda x: len(x)

df['Genre_count for Movie']=df.geners_arr.apply(count_lambda)
df.head(3)

Answer 1

Lambda functions are anonymous functions. The following two are equivalent:

def count_lambda(x):
    return len(x)

is the same as

count_lambda = lambda x: len(x)

See also https://docs.python.org/3/tutorial/controlflow.html#lambda-expressions