[英]R: Replacing multiple matches with matches
I am trying to shorten some regex matches in strings. 我正在尝试缩短字符串中的一些正则表达式匹配项。 Here is an example
这是一个例子
vYears = c('Democrat 2000-2004',
'Democrat 2004-2008',
'Democrat 2008-2012',
'Republican 2000-2004',
'Republican 2004-2008',
'Republican 2008-2012',
'Tossup')
I can match the expression that I want, and get the matches, like so 我可以匹配我想要的表达式,并得到匹配,就像这样
grepYears = gregexpr('20[0-9]{2}', vYears)
regmatches(vYears, grepYears)
However, I am trying to shorten the strings to 但是,我正在尝试将字符串缩短为
vYearsShort = c('Democrat 00-04',
'Democrat 04-08',
'Democrat 08-12',
'Republican 00-04',
'Republican 04-08',
'Republican 08-12',
'Tossup')
How can I achieve this? 我该如何实现?
You could use gsub
. 您可以使用
gsub
。 Make use of backreferences to capture the desired part: 利用反向引用捕获所需的部分:
> vYears = c('Democrat 2000-2004',
+ 'Democrat 2004-2008',
+ 'Democrat 2008-2012',
+ 'Republican 2000-2004',
+ 'Republican 2004-2008',
+ 'Republican 2008-2012',
+ 'Tossup')
> vYearsShort = gsub("20([0-9]{2})", "\\1", vYears)
> vYearsShort
[1] "Democrat 00-04" "Democrat 04-08" "Democrat 08-12" "Republican 00-04"
[5] "Republican 04-08" "Republican 08-12" "Tossup"
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