我有2台发电机并使用下一种方法& while循环通过它处理如下,
码
while end_of_loop = 'n':
try:
table1_row = next(table1_generator)
table2_row = next(table2_generator)
except StopIteration:
end_of_loop = 'y'
如何识别哪个迭代器对象没有行?
我试图比较2个表,每个表行都在生成器对象中。
def _compare(self):
end_of_table = 'N'
try:
while end_of_table =='N':
try:
if self.table1_key == self.table2_key:
print 'same key'
self.table1_row = next(self.table1_generator)
self._convert_table1_key_fields()
self.table2_row = next(self.table2_generator)
self._convert_table2_key_fields()
elif self.table1_key > self.table2_key:
self.table2_row = next(self.table1_generator)
self._convert_table2_key_fields()
elif self.table1_key < self.table2_key:
self.table1_row = next(self.table2_generator)
self._convert_table1_key_fields()
except StopIteration as e:
print e.args
print 'IterError'
end_of_table = 'y'
except StopIteration:
print 'Next Iteration'
答案 0 :(得分:4)
您可以向next
提供第二个“哨兵”值:
sentinel = object()
while end_of_loop = 'n':
table1_row = next(table1_generator,sentinel)
table2_row = next(table2_generator,sentinel)
#I don't account for the case where they could be exhausted at
#the same time. It's easy to add that if it matters though.
if table1_row is sentinel:
print "table1_generator gave up first"
#"break" might be more appropriate ...
#(Unless there more to the loop than this.)
end_of_loop = 'y'
elif table2_row is sentinel:
print "table2_generator gave up first"
end_of_loop = 'y'
答案 1 :(得分:2)
您没有提供有关上下文或您实际尝试的内容的详细信息,但听起来itertools.izip_longest可能对您的情况有用(并且更加pythonic)。您可以填写Nones
或其他合适的值。
答案 2 :(得分:1)
我想不出一个用例(关注分享?),但我会尝试将next
包装到我自己的函数中:
def mynext(it):
try:
return next(it)
except StopIteration:
raise StopIteration(it)
然后,例如,
a = iter([1,2,3,4,5])
b = iter([4,5,6,7])
try:
while True:
print mynext(a)
print mynext(b)
except StopIteration as e:
if e.args[0] == a: print 'a ended'
if e.args[0] == b: print 'b ended'