将日期划分为日，月和年

Question

l have 41 year-dataset and l would like to do some calculations by using these dataset but for this, l need to divide the date into day, month and year respectively.

example dataset(csv file data)

 date      stations     pcp
1.01.1979   6   1.071
2.01.1979   6   5.909
3.01.1979   6   9.134
1.01.1979   5   1.229
2.01.1979   5   0.014
3.01.1979   5   3.241

l need to convert these data in this:

day  month   year   stations   pcp
 1    01    1979     6         1.071
 2    01    1979     6         5.909
 3    01    1979     6         9.134

when l run code , it stops and l have to close it. No error message. how can l correct this? lma fresh user and probably ,there are many mistakes. l hope l can learn my mistake here.l made two try and lm not sure which one is correct here is my code:

from datetime import date, datetime, timedelta,time
import csv
import numpy as np

a=[]
dd=[]
mm=[]
yy=[]
with open('p2.csv') as csvfile:
    x=[]
    reader = csv.DictReader(csvfile,fieldnames=("date","stations","pcp"),delimiter=';', quotechar='|')
    for row in reader:
       x.append(row["date"])

#try1
for i in range(len (x)):
   day,month,year=a.split(x[i])
   d=int(day)
   m=int(month)
   y=int(year)
   dd.append(d)
   mm.append(m)
   yy.append(y)



#try2
"""for i in range(len(x)):
   an=x[i]
   y=datetime.datetime.strftime(an, '%Y')
   d=datetime.datetime.strftime(an, '%d')
   m=datetime.datetime.strftime(an, '%m')
   dd.append(d)
   mm.append(m)
   yy.append(y)"""

Answer 1

There are a few problems:

1. Your delimiter should be a comma instead of a semicolon if it's a CSV.
2. You are splitting on a date string instead of a delimiter when you call a.split(x[i]) . You probably want to split on a . , since that's what's separating the date fields.

Without changing too much code, the following code works for me. It wasn't clear from your question what you want to actually do with the data, but I tried to demonstrate how you would get it.

import csv

with open('p2.csv') as csvfile:
    reader = csv.DictReader(
        csvfile, fieldnames=('date', 'stations', 'pcp'), 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('.')
    print(day, month, year)

Output :

1 01 1979
2 01 1979
3 01 1979
1 01 1979
2 01 1979
3 01 1979

Answer 2

this script will get you a list of lists with your values and will also write the final list into a csv.

import csv

with open('p2.csv') as csvfile:
    x=[]
    reader = csv.reader(csvfile,delimiter=',', quotechar='|')
    for num, row in enumerate(reader):
      for i, item in enumerate(row):
        if i ==0:
          yy = []
          d, m, y = item.split('.')
          yy.append(d)
          yy.append(m)
          yy.append(y)

        else:
          yy.append(item)
      x.append(yy)
    print x       

with open('output.csv', 'wb') as csvfile:
    datawriter = csv.writer(csvfile,delimiter=',', quotechar='|')
    for datarow in x:
      datawriter.writerow(datarow)