我有一个URL链接列表，我想提取其中一个字符串并将其保存在另一个变量中。示例数据如下：
sample<- c("http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr01f2009.pdf",
"http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr02f2001.pdf",
"http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr03f2002.pdf",
"http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr04f2004.pdf",
"http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr05f2005.pdf",
"http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr06f2018.pdf",
"http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr07f2016.pdf",
"http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr08f2015.pdf",
"http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr09f2020.pdf",
"http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr10f2014.pdf")
sample
[1] "http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr01f2009.pdf"
[2] "http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr02f2001.pdf"
[3] "http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr03f2002.pdf"
[4] "http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr04f2004.pdf"
[5] "http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr05f2005.pdf"
[6] "http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr06f2018.pdf"
[7] "http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr07f2016.pdf"
[8] "http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr08f2015.pdf"
[9] "http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr09f2020.pdf"
[10] "http://dps.endavadigital.net/owgr/doc/content/archive/2009/owgr10f2014.pdf"
我想使用正则表达式提取一周和一年。
week year
1 1 2009
2 2 2001
3 3 2002
4 4 2004
5 5 2005
6 6 2018
7 7 2016
8 8 2015
9 9 2020
10 10 2014
您可以str_match在'owgr'和之后捕获数字'f'：
library(stringr)
str_match(sample, 'owgr(\\d+)f(\\d+)')[, -1]
您可以将其转换为数据框，将类更改为数字并分配列名称。
setNames(type.convert(data.frame(
str_match(sample, 'owgr(\\d+)f(\\d+)')[, -1])), c('year', 'week'))
# year week
#1 1 2009
#2 2 2001
#3 3 2002
#4 4 2004
#5 5 2005
#6 6 2018
#7 7 2016
#8 8 2015
#9 9 2020
#10 10 2014
另一种方法是从的最后一部分提取所有数字sample。我们可以通过获得最后一部分basename。
str_extract_all(basename(sample), '\\d+', simplify = TRUE)
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我来说两句