CODEWITHSUNDEEP
pythonpython-3.x
brt
brt

Reputation: 47

'int' object is not iterable, map() passing trough a list

So lets I have this list;

yy=[1,2,3,4,5,6,7,8,9,10]

and I want a map() to go through the list using the np.std() this,

np. std(1,2,3), std(2,3,4), std(3,4,5) .... std(8,9,10)

so I thought of doing something like this,

import numpy as np
y = [1,2,3,4,5,6,7,8,9,10]
n = 3
x = map(lambda w, n: np.std(y[x-n:x]), range(n,len(y)), n)
print(list(x))

But I get this error 'int' object is not iterable, how do I fix this?

Upvotes: 0

Views: 217

Answers (2)

Mark Ransom
Mark Ransom

Reputation: 308111

OK, now I see what you were trying to do. You expected the single value of n to be passed each time into your lambda function. But that's not how map works, it expects all its arguments to be iterables.

You had another problem, you are passing w into your lambda function but trying to use it as x.

Here's the version of your code with those two problems fixed:

x = map(lambda w, n: np.std(y[w-n:w]), range(n,len(y)), [n]*len(y))

You can simplify it by realizing that you don't need to pass n into the lambda function at all, it's already defined in the scope where you're creating the function.

x = map(lambda w: np.std(y[w-n:w]), range(n,len(y)))

Finally you can use a generator expression instead of map.

x = (np.std(y[w-n:w]) for w in range(n,len(y)))

Upvotes: 0

rdas
rdas

Reputation: 21275

You're passing too many iterables to map. You just need to pass the start index for each piece of the list that you want to np.std()

import numpy as np
y = [1,2,3,4,5,6,7,8,9,10]
n = 3
x = map(lambda i: np.std(y[i:i+n]), range(len(y) - n)) # pass only the start index for each iteration
print(list(x))

Result:

[0.816496580927726, 0.816496580927726, 0.816496580927726, 0.816496580927726, 0.816496580927726, 0.816496580927726, 0.816496580927726]

Upvotes: 3

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