python - 在 csv 文件的特定列中插入数据

Question

我正在尝试插入从日期列获得的数据。 csv 文件中的列标题为 date,day,month,year,pcp1,pcp2,pcp3,pcp4,pcp5,pcp6。 日、月、年列当前为空。

我想将通过分割方法从日期获得的数据插入到这些列中。我怎样才能做到这一点？

以下是 csv 文件中的示例数据:

date    day month   year    pcp1    pcp2    pcp3    pcp4    pcp5    pcp6
1.01.1979               0.431   2.167   9.375   0.431   2.167   9.375
2.01.1979               1.216   2.583   9.162   1.216   2.583   9.162
3.01.1979               4.041   9.373   23.169  4.041   9.373   23.169
4.01.1979               1.799   3.866   8.286   1.799   3.866   8.286
5.01.1979               0.003   0.051   0.342   0.003   0.051   0.342
6.01.1979               2.345   3.777   7.483   2.345   3.777   7.483
7.01.1979               0.017   0.031   0.173   0.017   0.031   0.173

这是我的代码:

import csv

dd=[]
mm=[]
yy=[]
with open('output2.csv') as csvfile:
            reader = csv.DictReader(csvfile, fieldnames=("date","day","month","year","pcp1","pcp2","pcp3","pcp4","pcp5","pcp6"), delimiter=';', quotechar='|')
            next(reader)  # skip header row
            x = [row['date'] for row in reader]

for date_str in x:
    day, month, year = date_str.split('.')
    dd.append(day)
    mm.append(month)
    yy.append(year)

csvfile.close()

with open('output2.csv') as f:
    fieldnames = ["date","day","month","year","pcp1","pcp2","pcp3","pcp4","pcp5","pcp6"]
    writer = csv.DictWriter(f, fieldnames=fieldnames,delimiter=';', quotechar='|')
    for i in range(len(dd)):
        writer.writerow({'day':dd[i]})
    for i in range(len(mm)):
        writer.writerow({'month':mm[i]})
    for i in range(len(yy)):
        writer.writerow({'year':yy[i]})


f.close()

Answer 1

您可以按如下方式解析 CSV。这会将所有行读取到列表中，然后将日期部分插入到空列中。

import csv

with open('output2.csv', newline='') as f_input:
    csv_input = csv.reader(f_input, delimiter=';', quotechar='|')
    header = next(csv_input)
    rows = list(csv_input)

with open('output2b.csv', 'w', newline='') as f_output:
    csv_output = csv.writer(f_output, delimiter=';', quotechar='|')
    csv_output.writerow(header)

    for row in rows:
        day, month, year = row[0].split('.')
        row[1:4] = [day, month, year]
        csv_output.writerow(row)

为您提供以下输出:

date;day;month;year;pcp1;pcp2;pcp3;pcp4;pcp5;pcp6
1.01.1979;1;01;1979;0.431;2.167;9.375;0.431;2.167;9.375
2.01.1979;2;01;1979;1.216;2.583;9.162;1.216;2.583;9.162
3.01.1979;3;01;1979;4.041;9.373;23.169;4.041;9.373;23.169
4.01.1979;4;01;1979;1.799;3.866;8.286;1.799;3.866;8.286
5.01.1979;5;01;1979;0.003;0.051;0.342;0.003;0.051;0.342
6.01.1979;6;01;1979;2.345;3.777;7.483;2.345;3.777;7.483
7.01.1979;7;01;1979;0.017;0.031;0.173;0.017;0.031;0.173

使用 Python 3.5.2 进行测试