Write an iterator that takes in two arguments, a function and a list. The iterator should return all elements starting from the first item that fails the predicate function. This means that you should eliminate all items from the beginning of the list that do satisfy the predicate. Here’s an example:

>>> d = DropWhile(lambda x: x < 5, [1, 4, 6, 4, 1])
>>> for i in d:
...     print(i)
class DropWhile(object):
    "***YOUR CODE HERE***"

Toggle Solution

class DropWhile(object):

    def __init__(self, pred, sequence):
        self.pred = pred
        self.sequence = sequence

    def __iter__(self):
        while self.sequence and self.pred(self.sequence[0]):
        return iter(self.sequence)

There are many ways to solve this problem. Basically, since we’re using a list, all we need to do is get rid of the elements at the beginning of the list that satisfy the predicate. Then, we just return the normal list iterator over the rest of the items in the list.

I don't claim to be perfect so if you find an error on this page, please send me an email preferably with a link to this page so that I know what I need to fix!

comments powered by Disqus