PySpark Evaluation

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It happens because of Python late binding and is not (Py)Spark specific. i will be looked-up when lambda p : int(p) + i is used, not when it is defined. Typically it means when it is called but in this particular context it is when it is serialized to be send to the workers.

You can do for example something like this:

def f(i):
    def _f(x):
        try:
            return int(x) + i
        except:
            pass
    return _f

data = sc.parallelize(["1", "2", "3"])
splits = [data.map(f(i)) for i in range(4)]
[rdd.collect() for rdd in splits]
## [[1, 2, 3], [2, 3, 4], [3, 4, 5], [4, 5, 6]]

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