如何將字符串放入列表？

Question

我嘗試使用csv.DictReader()將列數據之一編輯為所需的格式，代碼如下：

import csv
import time
with open('201701.csv') as inf:
        reader = csv.DictReader(inf)
        for row in reader:
            date = row['日期']
            d = date.split('/')
            year = int(d[0]) + 1911
            month = str(d[1])
            day = str(d[2])
            date_ = str(year) + "{0:2}".format(month) + "{0:2}".format(day)
            print(date_)

結果是這樣的：

20170103
20170104
20170105
20170106
20170109
20170110
20170111
20170112
20170113
20170116
20170117
20170118
20170119
20170120
20170123
20170124

但是我想要這樣的數據：

date_list = ['20170103', '20170104', '20170105', '20170106', '20170109', '20170110', '20170111', '20170112', '20170113', '20170116', '20170117', '20170118', '20170119', '20170120', '20170123', '20170124']

Answer 1

您的輸出是這樣的，因為您反復使用print(date_)打印單個字符串日期。 那根本不是清單。

要創建列表，請將您的日期字符串附加到列表date_list ：

import csv
import time
date_list = []    # create list of date
with open('201701.csv') as inf:with open('201701.csv') as inf:
        reader = csv.DictReader(inf)
        for row in reader:
            date = row['日期']
            d = date.split('/')
            year = int(d[0]) + 1911
            month = str(d[1])
            day = str(d[2])
            date_ = str(year) + "{0:2}".format(month) + "{0:2}".format(day)
            date_list.append(date_)  # append your date string to list
print(date_list)

Answer 2

您可以將其編寫為生成器。 這使您能夠遍歷文件中的日期序列，或將它們一起收集在列表中。 我簡化了您的代碼：

import csv
import time

def get_dates(inf):
    for row in csv.DictReader(inf):
        year, month, day = row['日期'].split('/')
        yield '{}{:02}{:02}'.format(int(year) + 1911, int(month), int(day))

用法：

# Collect into a list
with open('201701.csv') as inf:
    date_list = list(get_dates(inf))
    print(date_list)

# Or iterate over the dates
with open('201701.csv') as inf:
    for date in get_dates(inf):
        print(date)

Answer 3

好吧，如果您想要一個date_list那么您應該做一個！

import csv
import time
date_list = []
with open('201701.csv') as inf:with open('201701.csv') as inf:
    reader = csv.DictReader(inf)
    for row in reader:
        date = row['日期']
        d = date.split('/')
        year = int(d[0]) + 1911
        month = str(d[1])
        day = str(d[2])
        date_ = str(year) + "{0:2}".format(month) + "{0:2}".format(day)
        print(date_)
        date_list.append(date_)
print(date_list)