Question

我有以下代码。可以＆＃34; The Loop＆＃34;简化，以便我不必重复这些陈述？

topic1 = ["abc", "def"]
topic2 = ["ghi", "jkl", "mno"]
topic3 = ["pqr"]

outfile = open('topics_nodes.csv', 'w')
outfile.write("Node;Topic\n")

# The Loop
for i in topic1:
    print i
    outfile2.write(i +";1\n")
for i in topic2:
    print i
    outfile2.write(i +";2\n")
for i in topic1:
    print i
    outfile2.write(i +";3\n")

Answer 1

你可以这样做：

for index, topic_list in enumerate([topic1, topic2, topic3], 1):
    for i in topic_list:
        print i
        outfile2.write('{:d};{:d}\n'.format(i, index))

Answer 2

在这种情况下，Nessuno的答案已足够，但一般情况下，您可能还需要查看csv.writer类，该类提供了用于编写CSV文件的统一界面：

import csv

with open('topics_nodes.csv', 'w') as csvfile:
    writer = csv.writer(csvfile, delimiter=';')
    writer.writerow(('Node', 'Topic'))

    for topic, nodes in enumerate([topic1, topic2, topic3], 1):
        for node in nodes:
            print node
            writer.writerow((node, topic))

Answer 3

enumerate列表，然后遍历他们的项目。

>>> for i, li in enumerate((topic1, topic2, topic3), 1):
...     for x in li:
...         print(x, i)
... 
abc 1
def 1
ghi 2
jkl 2
mno 2
pqr 3

迭代一组列表，一次一个列表

3 个答案: