CODEWITHSUNDEEP
pythonpython-3.xlambdaanonymous-function
user415612
user415612

Reputation: 537

Print statement inside function used within lambda function not executing

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

Upvotes: 0

Views: 483

Answers (2)

user21858287
user21858287

Reputation: 1

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

Upvotes: 0

Patrick Artner
Patrick Artner

Reputation: 51683

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))

Upvotes: 1

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