使用 lambda 表达式理解 map() function 的概念

Question

What does this (x[1],0) part transform?

rdd.map(lambda x : (x[1],0))

Answer 1

For each item in rdd it creates a tuple. For that rdd item ( x ), the second value of that rdd item ( x[1] ), is placed in the tuple being created along with the number 0 .

I don't have pyspark installed, so I'm just using the built in map function to show how this transformation would work:

>>> rdd = ['ab', 'xyz', 'jk', 'pq']
>>> list(map(lambda x : (x[1],0), rdd)) 
[('b', 0), ('y', 0), ('k', 0), ('q', 0)]