Question

我有一个这种形式的字符串。我想将此字符串中括号内的数字增加15。

为此任务建议在R中使用一些正则表达式代码。在该论坛上已阅读有关从括号/括号中提取数字的信息。但是在这种特定情况下没有帮助。

String=
" John was going .[1]  Sam was Walking [2,3]. Rita was reading [4] . Donald was cooking with 3 spoons [5-7]"

所需的输出。

"John was going .[16]  Sam was Walking [17,18]. Rita was reading [19] Donald was cooking with 3 spoons [20-22]"

Answer 1

gsubfn与gsub相似，只是替换字符串是替换 function ，该替换 function 将匹配项作为输入，并将其替换为输出。可以使用公式符号（如此处所示）或常用功能符号来表示函数。

内部gsubfn接受一个[...]字符串，并将其中的数字替换为那些数字加上15，而外部gsubfn将[...]传递给内部数字。请注意，正则表达式\\[.*?\\]匹配左方括号\\[，后跟最短的字符串.*?，直到下一个右方括号\\]为止。

该解决方案是紧凑的（仅一行），仅使用相对简单的正则表达式，不会覆盖其输入，并且已向量化（即String可以是向量）。

library(gsubfn)

gsubfn("\\[.*?\\]", ~ gsubfn("\\d+", ~ as.numeric(x) + 15, x), String)
## " John was going .[16]  Sam was Walking [17,18]. Rita was reading [19] . Donald was cooking with 3 spoons [20-22]"

如果增加所有数字就足够了，那么可以简化为：

gsubfn("\\d+", ~ as.numeric(x) + 15, String)
## [1] " John was going .[16]  Sam was Walking [17,18]. Rita was reading [19] . Donald was cooking with 18 spoons [20-22]"

Answer 2

类似于@G。格洛腾迪克的答案也可以通过stringr的{{1}}函数轻松实现，该函数接受替换函数而不是常量。在这种情况下，只需要一个函数调用：

str_replace_all

输出：

library(stringr)

str_replace_all(String, "\\d+(?=[^\\[]*\\])", function(x) as.numeric(x) + 15)

或者是Base R解决方案：

[1] " John was going .[16]  Sam was Walking [17,18]. Rita was reading [19] . Donald was cooking with 3 spoons [20-22]"

输出：

pos <- gregexpr("\\d+(?=[^[]*\\])", String, perl = TRUE)
num <- as.numeric(regmatches(String, pos)[[1]]) + 15
regmatches(String, pos)[[1]] <- num

注释：

正则表达式[1] " John was going .[16] Sam was Walking [17,18]. Rita was reading [19] . Donald was cooking with 3 spoons [20-22]"匹配任何数字一次或多次（\\d+(?=[^[]*\\])），然后跟（\\d+）一系列非开括号字符零或更多次（(?=...)）和右括号（[^[]*）。有效地仅匹配括号内的数字。
\\]使用正则表达式并返回gregexpr中的所有匹配位置。 String启用环视功能。
perl = TRUE占据regmatches返回的位置，并返回实际的匹配字符串。
第二次调用gregexpr用于用regmatches

Answer 3

我的猜测是，也许我们可以使用此表达式进行统计以捕获数字：

\[(\d+(?:[,-]\d+)?)\]

然后，我们只需在其中添加15个。

如果您有兴趣，可以在this demo的右侧面板中进一步解释该表达式。

Answer 4

s = "John was going .[1]  Sam was Walking [2,3]. Rita was reading [4] . Donald was cooking with 3 spoons [5-7]"

import re

s = re.sub(r'\[([\d,-]+)\]', lambda g: re.sub(r'\d+', lambda gg: str(int(gg.group(0)) + 15), g.group(0)), s)

print(s)

打印：

John was going .[16]  Sam was Walking [17,18]. Rita was reading [19] . Donald was cooking with 3 spoons [20-22]

将括号/括号内的数字增加指定数量的功能

4 个答案: