r-从每个字段中删除最后一个字符 [英] r - remove last but one character from every field

问题描述

R中的substr()函数可以按位置隔离任何字符，例如

the substr() function in R can isolate any character by position e.g.

substr(df$10,2,3)

或通过使用nchar()，可以从字段的末尾向后进行操作，以将某个字符隔离在最后一个位置，但使用以下一个来隔离字符:

or by using nchar() it is possible to work backwards from the end of the field to isolate a character in a position such as last but one using:

substr(df$10,nchar(df$10)-2,nchar(df$10)-1)

但是我想知道如何简单地删除数据框中列的每个字段的last but one character.我很难做到这一点.任何帮助都会很棒！

however I would like to know how to simply remove the last but one character of every field for a column in a dataframe. I am having difficulty doing this. any help would be great!

推荐答案

您可以对sub使用正则表达式:

You can use a regular expression with sub:

x <- c("banana","republic")
sub(".(.)$","\\1",x)
[1] "banaa"   "republc"

此操作将匹配字符串中的最后两个字符，并仅将其替换为捕获组中捕获的最后一个字符.

What this does is match the last two characters in a string, and replace them with only the last one, which is captured in a capture group.

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