实现for循环：如果值正在更改，则执行某些操作（即生成行）

Question

我有以下三个清单：

ov = [1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1]

participant = [1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4, 4]

geom = ['0101000020E864000077C385FFB4231C417F437ECE83E95441', '0101000020E8640000F532AC46BA231C41A945335C84E95441', '0101000020E8640000CD138FFA46EA1A41C71D074C27E15441', '0101000020E864000087373742A94A1A41B6A39D38B0815441', '0101000020E86400003A60EE21A3231C41ACB8FFA584E95441', '0101000020E864000046717DBEB2231C4115840F5D84E95441', '0101000020E8640000AAAF4E36AB231C413AC5EB5D84E95441', '0101000020E8640000B84BD7B961231C41D245C83B85E95441', '0101000020E864000026940AB784231C417B5D79A984E95441', '0101000020E86400003FE809B587231C4102DB987E85E95441', '0101000020E8640000B8FC550A83231C41E5B0F93785E95441', '0101000020E8640000E1A849F9A1231C41009C21A684E95441', '0101000020E8640000E1A849F9A1231C41009C21A684E95441', '0101000020E864000066EB7C29A0231C41F29756A684E95441', '0101000020E86400009B3CC349DC711C41EE7E428C76E15441', '0101000020E86400008985282945681C4182B65E6F50DC5441', '0101000020E86400005B469B1AB1711C410553435A76E15441']

现在我想在以下条件下创建行：

• 使用geom作为点，线通常在ov为1时开始，在ov为0时结束

• 除非参与者发生变化，否则新行开始

所以在我的例子中，我想使用geom创建线字符串，其中ov是：

linestring 1: 1, 0
linestring 2: 1, 1, 1, 1, 1, 0
linestring 3: 1, 1, 1, 0
linestring 4: 1, 1, 1
linestring 5: 1, 1

我曾想过使用for循环来实现这一点，但我不知道如何实现它：如果值正在更改，那么停止并生成一行。你知道吗

注意：问题不在于如何生成一行，而在于如何在实现中使用所有正确的值。你知道吗

希望我能解释清楚，有人能帮我，提前谢谢！你知道吗

Answer 1

您可以使用zip来组合这3个列表。你知道吗

entries = zip(ov,participant,geom)
for entry in entries:
    # for the first entry it should print 1,1,0101000020E864000077C385FFB4231C417F437ECE83E95441
    print(entry)

Answer 2

假设participant始终是排序的，请使用itertools.groupby根据其元素对项目进行分组：

for k, g in groupby(zip(participant, ov, geom), itemgetter(0)):
    # k: element of participant
    # g: all (participant, ov, geom) items corresponding to k

要打印每一行，请将(ov, geom)元素与g（迭代器）分开，并用逗号连接：

# each (ov, geom)  > "ov, geom"
line = ', '.join(map(lambda x: str(x[1])+', '+x[2], g))

完整代码：

from itertools import groupby
from operator import itemgetter

for k, g in groupby(zip(participant, ov, geom), itemgetter(0)):
    print('linestring %i:' % k, ', '.join(map(lambda x: '%s, %i' % x[1:], g)))

输出：

linestring 1: 1, 0101000020E864000077C385FFB4231C417F437ECE83E95441, 0, 0101000020E8640000F532AC46BA231C41A945335C84E95441
linestring 2: 1, 0101000020E8640000CD138FFA46EA1A41C71D074C27E15441, 1, 0101000020E864000087373742A94A1A41B6A39D38B0815441, 1, 0101000020E86400003A60EE21A3231C41ACB8FFA584E95441, 1, 0101000020E864000046717DBEB2231C4115840F5D84E95441, 1, 0101000020E8640000AAAF4E36AB231C413AC5EB5D84E95441, 0, 0101000020E8640000B84BD7B961231C41D245C83B85E95441
linestring 3: 1, 0101000020E864000026940AB784231C417B5D79A984E95441, 1, 0101000020E86400003FE809B587231C4102DB987E85E95441, 1, 0101000020E8640000B8FC550A83231C41E5B0F93785E95441, 0, 0101000020E8640000E1A849F9A1231C41009C21A684E95441, 1, 0101000020E8640000E1A849F9A1231C41009C21A684E95441, 1, 0101000020E864000066EB7C29A0231C41F29756A684E95441, 1, 0101000020E86400009B3CC349DC711C41EE7E428C76E15441
linestring 4: 1, 0101000020E86400008985282945681C4182B65E6F50DC5441, 1, 0101000020E86400005B469B1AB1711C410553435A76E15441

为清晰起见，在单独的行上打印每对项目：

linestring 1:
   1, 0101000020E864000077C385FFB4231C417F437ECE83E95441
   0, 0101000020E8640000F532AC46BA231C41A945335C84E95441
linestring 2:
   1, 0101000020E8640000CD138FFA46EA1A41C71D074C27E15441
   1, 0101000020E864000087373742A94A1A41B6A39D38B0815441
   1, 0101000020E86400003A60EE21A3231C41ACB8FFA584E95441
   1, 0101000020E864000046717DBEB2231C4115840F5D84E95441
   1, 0101000020E8640000AAAF4E36AB231C413AC5EB5D84E95441
   0, 0101000020E8640000B84BD7B961231C41D245C83B85E95441
linestring 3:
   1, 0101000020E864000026940AB784231C417B5D79A984E95441
   1, 0101000020E86400003FE809B587231C4102DB987E85E95441
   1, 0101000020E8640000B8FC550A83231C41E5B0F93785E95441
   0, 0101000020E8640000E1A849F9A1231C41009C21A684E95441
   1, 0101000020E8640000E1A849F9A1231C41009C21A684E95441
   1, 0101000020E864000066EB7C29A0231C41F29756A684E95441
   1, 0101000020E86400009B3CC349DC711C41EE7E428C76E15441
linestring 4:
   1, 0101000020E86400008985282945681C4182B65E6F50DC5441
   1, 0101000020E86400005B469B1AB1711C410553435A76E15441