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)

我得到奇怪的输出！这段代码有什么问题？

Answer 1

我就是这样做的

 import csv
    file = open('???.csv', 'r')
    read = csv.reader(file)
    for column in read:
            file = open('???.csv', 'r')
            read = csv.reader(file)
            file.close()
            file = open('????.csv', 'a', newline='')
            write = csv.writer(file, delimiter = ",")
            write.writerow((, ))
            file.close()

Answer 2

这将提供准确的输出

import csv

import collections

with open('file.csv', 'rb') as f:

  data = list(csv.reader(f))

counter = collections.defaultdict(int)

for row in data:

    counter[row[0]] += 1

writer = csv.writer(open("file1.csv", 'w'))

for row in data:

    if counter[row[0]] >= 1:

        writer.writerow(row)

Answer 3

您可以关闭文件而不是 csv.writer 对象，它应该是：

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

Answer 4

一个简单的例子是这样的：

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

Answer 5

使用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 6

使用熊猫

   df.to_csv("your_preferred_name.csv")

Answer 7

我知道问题是询问您的“csv”包实现，但为了您的信息，有一些更简单的选项 - 例如 numpy。

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

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（这个答案是在 6 年后发布的，为了子孙后代。）

在与您所询问的情况类似的不同情况下，假设您有两列，如下所示：

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

您可以像这样保存它：

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