Question

我遇到了csv文件的问题，我需要一些信息。以下是我需要做的事情：

我有一个像这样订购的CSV文件：

bla country bla bla    value 
    Germany               Y
    Germany               Y
    Germany               N 
    Denmark               N
    Denmark               N
    Denmark               Y

现在我想用python做的每次Y值都在同一列中。所以最后我得到了像德国这样的东西：2丹麦：1。

但是，我只能使用以下代码弄清楚如何计算列：

import csv
from collections import Counter, defaultdict
from itertools import imap
from operator import  itemgetter



header_counter = defaultdict(Counter)

with open('airlines.csv') as input_file:
  r = csv.reader(input_file, delimiter=',')

  headers = next(r)
  for row in r:

      row_val = sum([w.isdigit() for w in row])

      for header, val in zip(headers, row):

          if not any(map(str.isdigit, val)):
              header_counter[header].update({val: row_val})


for k, v in header_counter.iteritems():
   print k, v

我认为上面的代码对任何人都有很大用处，因为它只计算每列的行数并过滤掉整数。我能得到的任何帮助都非常感谢，我仍然相当缺乏经验。

Answer 1

这是你要找的吗？

import csv
from collections import Counter

data = '''country,value
Germany,Y
Germany,Y
Germany,N 
Denmark,N
Denmark,N
Denmark,Y'''

r = csv.DictReader(data.split('\n'))

counter = Counter(
    row.get('country')
    for row in r
    if row.get('value') == 'Y')

for k, v in counter.items():
    print('{}: {}'.format(k, v))

Answer 2

我认为@ smarx的答案是最美妙的方式。这是一个更冗长和实用的方法：

import csv

d = {}

with open('airlines.csv', 'r') as f:
    # Sniff the CSV dialect
    dialect = csv.Sniffer().sniff(f.read(1024))

    # Move back to beginning of file
    f.seek(0)

    # DictReader uses the first row in the file as headers.
    r = csv.DictReader(f, dialect=dialect)

    # Plain iteration and counting in a normal dict.
    for row in r:
        # Plain incrementation of the "country" by one if "value" is
        # 'Y'
        if row['value'] == 'Y':
            d[row['country']] = d.get(row['country'], 0) + 1

for k in d:
    print('{} => {}'.format(k, d[k]))

CSV：如果另一列具有特定值，则计算列中的字符串

2 个答案: