Question

import csv
with open("somecities.csv", "r") as csvinput:
    with open(" somecities_update.csv", "w") as csvresult:
        writer = csv.writer(csvresult, lineterminator='\n')
        reader = csv.reader(csvinput)
        all = []
        headers = next(reader)
        for row in reader:
            all.append(row)

        # writing to the new file from here
        writer.write(headers)
        for record in all:
            writer.write(record)

somecities.csv内容：

Country,Capital,CountryPop,AreaSqKm

Canada,Ottawa,35151728,9984670

USA,Washington DC,323127513,9833520

Japan,Tokyo,126740000,377972

Luxembourg,Luxembourg City,576249,2586

我要添加的somecities_update数据：

(Brazil, Brasília, 211224219, 8358140)

(China, Beijing, 1403500365, 9388211)

(Belgium, Brussels, 11250000, 30528)

在遍历包含数据的旧CSV文件的过程中，我已经走了这么远，但是现在我不无处获取新数据并将其打印在somecities_update.csv中。我应该如何完成此代码？

Answer 1

我假设您想将“ somecities_update.csv”的记录追加到“ somecities.csv”的末尾。

为此，您可以在追加模式（mode='a'）中打开“ somecities.csv”文件，从“ somecities_update.csv”中读取每一行并将其复制到somecities.csv”中。

以下代码演示了此插入：

import io
import csv

with io.open("somecities.csv", mode='a', encoding='utf-8') as dst:
    writer = csv.writer(dst, lineterminator='\n')
    with io.open(
            "somecities_update.csv", mode='r', encoding='utf-8') as src:
        reader = csv.reader(src)
        headers = next(reader)
        for record in reader:
            writer.writerow(record)

警告：仅当“ somecities.csv”文件已经存在时，此脚本才有效。否则，将不会生成标题。

注意：您需要使用writer.writerow。

Python-将数据追加到CSV并打印到新的CSV

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