Python：如何将字典值解析为2个单独的值，以便我可以导出为.csv？

Question

I am looking to find the closest subway station to a Craigslist apt listing and the distance (in miles) from the listing. I would like to export this as a .csv file for further analysis.

I have written the following in python:

1. Script to scrape Craigslist listings. Includes latitude and longitude of each listing. Saved as .csv file
2. Script to scrape list of subway stations. Includes latitude and longitude of each station. Saved as .csv file
3. Script that takes these 2 .csv files, and calculates the distance of each pair of coordinates. For each listing, find the closest subway station, and the corresponding distance

`Code:

import csv
from geopy.distance import vincenty
from operator import itemgetter

with open('coord.csv') as csvfile:
    #skip first line in csv
    next(csvfile)
    #read csv
    readCSV = csv.reader(csvfile, delimiter=',')
    #store results in a dictionary
    subwayCoords = {}
    #loop through each row in csv
    for row in readCSV:
        subway = row[1]
        s_coord = row[0],row[3]

        subwayCoords[subway] = s_coord

with open('items.csv') as csvfile:
    next(csvfile)
    readCSV = csv.reader(csvfile, delimiter=',')
    craigCoords = {}
    for row in readCSV:
        craigID = row[1]
        c_coord = row[11]

        craigCoords[craigID] = c_coord


craigDist = {}  #dictionary: distance between each listing and subway
craigMin = {}   #dictionary: nearest subway to each listing


#get each listing's coordinates (key=listing, value=coordinates)
for craigID, c_coord in craigCoords.items():
    #get each subway's coordinates (key=subway, value=coordinates)
    for subway, s_coord in subwayCoords.items():
        #calculate distance between each listing and subway
        dist = vincenty(s_coord, c_coord).miles
        print "distance between " + ''.join(str(craigID)) + " and " + ''.join(str(subway)) + " = " + str(dist)

        craigDist[subway] = dist

    #for each listing, calculate closest subway; returns subway, distance as a tuple
    minPair = min(craigDist.iteritems(), key=itemgetter(1))

    craigMin[craigID] = minPair

    print craigMin

#export craigMin dictionary
with open('mycsvfile.csv','wb') as csvfile:
    w = csv.writer(csvfile)
    w.writerows(craigMin.items())

I now have a dictionary with key, value pairs as follows:

{listing: (closest subway station, distance),...}

Run-time output:

{
  '6022151897': ('Kew Gardens\xe2\x80\x93Union Turnpike (IND Queens Boulevard Line)', 1.1243919326522678), 
  '6022258759': ('Forest Hills\xe2\x80\x9371st Avenue (IND Queens Boulevard Line)', 0.20148597888760844), 
  '6022892363': ('Vernon Boulevard\xe2\x80\x93Jackson Avenue (IRT Flushing Line)', 0.37261054608700767)
}

.csv output:

6022151897,"('Kew Gardens\xe2\x80\x93Union Turnpike (IND Queens Boulevard Line)', 1.1243919326522678)" 
6022258759,"('Forest Hills\xe2\x80\x9371st Avenue (IND Queens Boulevard Line)', 0.20148597888760844)" 
6022892363,"('Vernon Boulevard\xe2\x80\x93Jackson Avenue (IRT Flushing Line)', 0.37261054608700767)"

Note that the value contains 2 values, instead of one.

How do I get the value to be parsed as 2 separate values so I can export as a .csv? Any other tips for making the script more efficient would also be appreciated.

Answer 1

try this, it should flatten it and write your csv:

with open('mycsvfile.csv','wb') as csvfile:
    w = csv.writer(csvfile)
    for key, value in craigMin.items():
        w.writerows([key, value[0], value[1]])

Idea being, you have to pull the item in the dictionary apart.

Output of this approach:

6022151897, Kew Gardens–Union Turnpike (IND Queens Boulevard Line), 1.124391933

After I parsed out your comment you said this:

I tried this, and the output of my .csv looks the same:

6022151897,"('Kew Gardens\xe2\x80\x93Union Turnpike (IND Queens Boulevard Line)', 1.1243919326522678)"  
6022258759,"('Forest Hills\xe2\x80\x9371st Avenue (IND Queens Boulevard Line)', 0.20148597888760844)"  
6022892363,"('Vernon Boulevard\xe2\x80\x93Jackson Avenue (IRT Flushing Line)',
0.37261054608700767)" 

What I am looking for is clean text in value[0] and value[1]. For example, value[0] = Kew Gardens\\xe2\\x80\\x93Union Turnpike (IND Queens Boulevard Line. No extra () or " or '. Likewise, value[1] = 1.1243919326522678

What I am trying to convey is that the approach I gave you is very different than the code you have in your question. There's an entire loop that unpacks the dictionary instead of just shoving the .items() tuple into the csv.

I ran your code and got your result, you can't be doing what I suggested if thats the output you're getting, as far as I can tell.

Can you post your approach where you say "I tried this..."