问在文件结束前插入文本n行
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Stack Overflow用户

提问于 2021-02-20 09:57:27

回答 2查看 657关注 0票数 0

我有这个文件，我希望能够在python文件结束之前编写文本n行，我知道写方法是存在的，但是它只在文件的末尾插入文本。我想做这样的事情：

INSERT INTO `mod238_yoast_seo_meta` VALUES("12749", "0", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12755", "0", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12757", "1", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12765", "1", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12774", "1", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12785", "1", "0");

/* I would like to be able to insert some text here with python/*

SET FOREIGN_KEY_CHECKS = 1; 

/* Duplicator WordPress Timestamp: 2021-01-08 15:49:50*/
/* DUPLICATOR_MYSQLDUMP_EOF */

/* DUPLICATOR_MYSQLDUMP_EOF */是文件的最后一行，非常感谢！此外，我还使用python3.8。

text-manipulation

python-3.x

回答 2

Stack Overflow用户

回答已采纳

发布于 2021-02-20 10:17:35

处理此问题的一种方法是将文件读入行列表中。插入您想要的位置的新行。然后将这一系列行写到一个新文件中。

如果您知道要插入的行号，则可以直接使用该位置。如果需要根据文件底部的行数计算行位置，则可以将行位置计算为总行数和N行数之间的差额。

可能是这样的：

    # Insert text n lines before the end of file

    file_path = 'text.txt'
    line_to_insert = '/*this is my inserted line*/\n'
    lines_from_bottom = 4

    with open(file_path) as file:
        lines = file.readlines()
        insert_position = len(lines) - lines_from_bottom
        lines.insert(insert_position, line_to_insert)
        with open('new_file.txt', 'w') as new_file:
            for line in lines:
                new_file.write(line)

票数 0

Stack Overflow用户

发布于 2021-02-20 10:09:00

如果您知道必须跳过多少行，从结尾开始，只需逐行拆分源文本，添加新文本，然后重新连接：

source_text = '''INSERT INTO `mod238_yoast_seo_meta` VALUES("12749", "0", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12755", "0", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12757", "1", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12765", "1", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12774", "1", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12785", "1", "0");

SET FOREIGN_KEY_CHECKS = 1; 

/* Duplicator WordPress Timestamp: 2021-01-08 15:49:50*/
/* DUPLICATOR_MYSQLDUMP_EOF */'''

custom_text = "my new cool text"
lines_before = 5 # you want to add the new text 5 lines before the end

lines = source_text.split('\n')
lines.insert(-lines_before, "\n" + custom_text)
new_text = "\n".join(lines)

print(new_text)

否则，您可以为此使用正则表达式：

import re

source_text = '''INSERT INTO `mod238_yoast_seo_meta` VALUES("12749", "0", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12755", "0", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12757", "1", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12765", "1", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12774", "1", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12785", "1", "0");

SET FOREIGN_KEY_CHECKS = 1; 

/* Duplicator WordPress Timestamp: 2021-01-08 15:49:50*/
/* DUPLICATOR_MYSQLDUMP_EOF */'''

custom_text = "my new cool text"
new_text = re.sub("\s+(?=SET FOREIGN_KEY_CHECKS)", "\n\n%s\n\n" % custom_text, source_text)

print(new_text)

这两种方法都将打印：

INSERT INTO `mod238_yoast_seo_meta` VALUES("12749", "0", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12755", "0", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12757", "1", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12765", "1", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12774", "1", "0");
INSERT INTO `mod238_yoast_seo_meta` VALUES("12785", "1", "0");

my new cool text

SET FOREIGN_KEY_CHECKS = 1;

/* Duplicator WordPress Timestamp: 2021-01-08 15:49:50*/
/* DUPLICATOR_MYSQLDUMP_EOF */