使用Python将结果保存到csv文件

Question

import csv

with open('test.csv', 'rb') as f:
  data = list(csv.reader(f))

import collections
counter = collections.defaultdict(int)
for row in data:
    counter[row[1]] += 1
for row in data:
    if counter[row[1]] >= 4:
      writer = csv.writer(open("test1.csv", "wb"))
      writer.writerows(row)

我的输出很奇怪!这段代码有什么问题？

Answer 1

我知道问题是询问你的"csv"包实现,但是对于你的信息,有一些选项更加简单 - 例如,numpy.

import numpy as np
np.savetxt('data.csv', (col1_array, col2_array, col3_array), delimiter=',')

(这个答案在6年后发布,为了后人的缘故.)

在另一种情况下,假设您有两列,如下所示:

names = ['Player Name', 'Foo', 'Bar']
scores = ['Score', 250, 500]

你可以像这样保存它:

np.savetxt('scores.csv', [p for p in zip(names, scores)], delimiter=',', fmt='%s')

scores.csv 看起来像这样:

Player Name,Score
Foo,250
Bar,500

Answer 2

用途csv.writer:

import csv

with open('thefile.csv', 'rb') as f:
  data = list(csv.reader(f))

import collections
counter = collections.defaultdict(int)
for row in data:
    counter[row[0]] += 1


writer = csv.writer(open("/path/to/my/csv/file", 'w'))
for row in data:
    if counter[row[0]] >= 4:
        writer.writerow(row)

Answer 3

使用熊猫

   df.to_csv("your_preferred_name.csv")

Answer 4

您可以关闭文件而不是csv.writer对象，应该是：

f = open(fileName, "wb")
writer = csv.writer(f)
String[] entries = "first*second*third".split("*");
writer.writerows(entries)
f.close()