从下划线分隔的字符串中提取第n个元素

发表时间：2022-07-20 00:07:36 阅读：80

我想提取myproducta和myproductb.

我认为用正则表达式可以，但只适用于:cc string，但不适用于aa.怎么会这样？两者长度相同.

aa <- "e220juju_uk_yy_aon_aon_conversion_mystore_facebook-network_ppl_primaria_myproducta_galaxycombos_20220520"
cc <- "e220tyty_bo_oo_aon_aon_conversion_mystore_facebook-network_ppl_lal_myproductb_wd95m4473mw_diasdecyber_20220718"

正则表达式部分:

gsub(cc, pattern = ".*_.*_.*_.*_.*_.*_.*_.*_.*_(.*)_.*_.*_.*", replacement = "\\1", perl = TRUE) #works: returns: myproductb

gsub(aa, pattern = ".*_.*_.*_.*_.*_.*_.*_.*_.*_(.*)_.*_.*_.*", replacement = "\\1", perl = TRUE) #don't work: returns: primaria

🎖️ 优质答案

以下是一些方法

read.table(text = aa, sep = "_")[[11]]
## [1] "myproducta"

strsplit(aa, "_")[[1]][11]
## [1] "myproducta"

scan(text = aa, sep = "_", what = "", quiet = TRUE)[11]
## [1] "myproducta"

sub("^(([^_]*)_){10}([^_]*)_.*", "\\3", aa)
## [1] "myproducta"

You can use anchors and a negated character class, and then repeat 10 times matching an underscore before capturing the 11th occurrence.

^(?:[^_]*_){10}([^_]*).*$

Regex demo | R demo

aa <- "e220juju_uk_yy_aon_aon_conversion_mystore_facebook-network_ppl_primaria_myproducta_galaxycombos_20220520"
cc <- "e220tyty_bo_oo_aon_aon_conversion_mystore_facebook-network_ppl_lal_myproductb_wd95m4473mw_diasdecyber_20220718"

pattern <- "^(?:[^_]*_){10}([^_]*).*$"

gsub(pattern, "\\1", aa, perl = TRUE)
gsub(pattern, "\\1", cc, perl = TRUE)

Output:

[1] "myproducta"
[1] "myproductb"