有序字典和排序

Question

我正在尝试解决一个简单的练习题：

Parse the CSV file to:

Find only the rows where the user started before September 6th, 2010.

Next, order the values from the "words" column in ascending order (by start date)

Return the compiled "hidden" phrase

csv文件有19列1000行数据。其中大部分是无关紧要的。正如问题所述，我们只关心按升序对 start_date 列进行排序，以从 'words' 列中获取关联的词。将这些词组合在一起将得到 "hidden" 短语。

源文件中的日期是 UTC 时间格式，所以我不得不转换它们。我现在正处于我认为我已经选择了正确行的地步，但是我在对日期进行排序时遇到了问题。

这是我的代码：

import csv
from collections import OrderedDict
from datetime import datetime


with open('TSE_sample_data.csv', 'rb') as csvIn:
    reader = csv.DictReader(csvIn)
    for row in reader:

        #convert from UTC to more standard date format
        startdt = datetime.fromtimestamp(int(row['start_date']))
        new_startdt = datetime.strftime(startdt, '%Y%m%d')        

        # find dates before Sep 6th, 2010
        if new_startdt < '20100906':

            # add the values from the 'words' column to a list 
            words = []
            words.append(row['words'])

            # add the dates to a list
            dates = []
            dates.append(new_startdt)

            # create an ordered dictionary to sort the dates... this is where I'm having issues 
            dict1 = OrderedDict(zip(words, dates))
            print dict1
            #print list(dict1.items())[0][1]
            #dict2 = sorted([(y,x) for x,y in dict1.items()])
            #print dict2

当我 print dict1 我希望有一本有序的字典，其中包含单词和日期作为项目。相反，我得到的是为每个创建的键值对创建多个有序字典。

Answer 1

这是更正后的版本：

import csv
from collections import OrderedDict
from datetime import datetime


with open('TSE_sample_data.csv', 'rb') as csvIn:
    reader = csv.DictReader(csvIn)
    words = []
    dates = []
    for row in reader:

        #convert from UTC to more standard date format
        startdt = datetime.fromtimestamp(int(row['start_date']))
        new_startdt = datetime.strftime(startdt, '%Y%m%d')        

        # find dates before Sep 6th, 2010
        if new_startdt < '20100906':

            # add the values from the 'words' column to a list 
            words.append(row['words'])
            # add the dates to a list
            dates.append(new_startdt)

    # This is where I was going wrong! Had to move the lines below outside of the for loop
    # Originally, because I was still inside the for loop, I was creating a new Ordered Dict for each "row in reader" that met my if condition
    # By doing this outside of the for loop, I'm able to create the ordered dict storing all of the values that have been found in tuples inside the ordered dict
    # create an ordered dictionary to sort by the dates
    dict1 = OrderedDict(zip(words, dates))
    dict2 = sorted([(y,x) for x,y in dict1.items()])

    # print the hidden message
    for i in dict2: 
        print i[1]

有序字典和排序

Ordered Dictionary and Sorting

python

sorting

for-loop

dictionary

ordereddictionary