Stopping list selection? [duplicate]

Answer 1

Here's a slightly hacky to implement takewhile as part of a generator expression:

def stop(): raise StopIteration

result = (
    stop() if item[1] == -1 else
    item
    for item in s
    if item[0] >= X
)

Or with different phrasing:

def until(cond):
    if cond: raise StopIteration
    return True

result = (
    item for item in s
    if item[0] >= X
    and until(item[1] == -1)
)