Print statement inside function used within lambda function not executing

Question

In the code below, gen_window has a print statement in it but when I run the code the print statement doesn't get executed. Why is that and then how should I go about debugging such lambda functions? (Even the debugger ignores the breakpoint in these functions.)

getpairs = rdd.flatMap(lambda xi: gen_window(xi, n))


def gen_window(xi, n):
    x, i = xi
    l = []
    for offset in range(n):
        print("-->", (i - offset, (i, x)))
        l.append((i - offset, (i, x)))
    return l

@vs97 This isa part of larger code. I just hard code n as 3 for testing. Would you like me to post more code? I unfortunately can't post all of the code. — user415612
– user415612, Commented Feb 12, 2019 at 20:44

Patrick Artner · Accepted Answer · 2019-02-12 20:57:41Z

1

Works:

def gen_window(xi, n):
    x, i = xi
    l = []
    for offset in range(n):
        print("-->", (i - offset, (i, x)))
        l.append((i - offset, (i, x)))
    return l

xi = [3,5]
n = 3

gen_window(xi, n)

Lambdas only get executed wenn you actually use them - If you get no output you are probably never using it.

Output:

--> (5, (5, 3))
--> (4, (5, 3))
--> (3, (5, 3))

answered Feb 12, 2019 at 20:57

Patrick Artner

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Comments

user21858287 · Accepted Answer · 2023-05-09 04:39:36Z

0

Lambda functions always return an iterator hence you would have to wrap that lambda call into a list

Define a function that returns the length of a string

def string_length(s): length = len(s) print(f"The length of '{s}' is {length}") return length

Define a list of strings

strings = ["hello", "world", "python"]

Apply the function to each element in the list using map and a lambda function,

then convert the result to a list

lengths = list(map(lambda x: string_length(x), strings))

Print the resulting list of lengths

print(lengths) This would execute the print statements

Define a function that returns the length of a string

def string_length(s): length = len(s) print(f"The length of '{s}' is {length}") return length

Define a list of strings

strings = ["hello", "world", "python"]

Apply the function to each element in the list using map and a lambda function,

then convert the result to a list

lengths = map(lambda x: string_length(x), strings)

Print the resulting list of lengths

print(lengths)

But this would not

answered May 9, 2023 at 4:39

user21858287

1

1 Comment

Bob liao Over a year ago

please format it.

Collectives™ on Stack Overflow

Print statement inside function used within lambda function not executing

2 Answers 2

Comments

Define a function that returns the length of a string

Define a list of strings

Apply the function to each element in the list using map and a lambda function,

then convert the result to a list

Print the resulting list of lengths

Define a function that returns the length of a string

Define a list of strings

Apply the function to each element in the list using map and a lambda function,

then convert the result to a list

Print the resulting list of lengths

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Define a function that returns the length of a string

Define a list of strings

Apply the function to each element in the list using map and a lambda function,

then convert the result to a list

Print the resulting list of lengths

Define a function that returns the length of a string

Define a list of strings

Apply the function to each element in the list using map and a lambda function,

then convert the result to a list

Print the resulting list of lengths

1 Comment

Your Answer

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