匹配并提取 r 中的子字符串

Question

我有一个字符一行一行的文本数据，里面全是字符串

[1]"1128=9,9=282,35=X,34=4846318,52=20140107224500037,34=20140107,268=3,279=0,22=8,48=637548,83=585590,107=ZCH4,269=4,270=425,273=224500000,286=5,279=0,22=8,48=637548,83=585591,107=ZCH4,269=E,273=425.5,273=224500000,279=0,273=8,48=637548,34=585592,107=ZCH4,269=F,270=425,271=100,273=224500000,10=144"
[2]"1128=9,9=467,35=X,34=4846344,52=20140107224500107,75=20140108,268=5,279=0,22=8,48=772825,279=0,22=8,48=692825,83=434250,107=ZCZ4,269=E,270=453,271=41,273=224500000,279=0,22=8,48=692007,83=434251,107=ZCZ4,269=F,270=452.75,273=224500000,279=0,22=8,48=35213,83=434252274=2,336=0,451=0.25,279=1,22=8,48=692825,83=434253,107=ZCZ4,269=1,270=453,271=51,273=224500000,336=0,346=17,1023=1,10=239"

我想截断数据，只提取以“48=”和“34=”开头的子字符串，

我当前的代码是：

ex_between(data, c('48=', '34='), c(',', ','), extract=TRUE)

它有效，但它也截断了我想保留的“48=”和“34=”部分。

期望的结果：

[1]"34=4846318,34=20140107,48=637548,48=637548,48=637548,34=585592"
[2]34=4846344,48=772825,48=692825,48=692007,48=35213,48=692825"

截断数据中元素“34=....”和“48=....”的顺序需要与原始数据中的顺序相同。

Answer 1

怎么样：

# Sample strings
x <- c("1128=9,9=282,35=X,34=4846318,52=20140107224500037,34=20140107,268=3,279=0,22=8,48=637548,83=585590,107=ZCH4,269=4,270=425,273=224500000,286=5,279=0,22=8,48=637548,83=585591,107=ZCH4,269=E,273=425.5,273=224500000,279=0,273=8,48=637548,34=585592,107=ZCH4,269=F,270=425,271=100,273=224500000,10=144",
"1128=9,9=467,35=X,34=4846344,52=20140107224500107,75=20140108,268=5,279=0,22=8,48=772825,279=0,22=8,48=692825,83=434250,107=ZCZ4,269=E,270=453,271=41,273=224500000,279=0,22=8,48=692007,83=434251,107=ZCZ4,269=F,270=452.75,273=224500000,279=0,22=8,48=35213,83=434252274=2,336=0,451=0.25,279=1,22=8,48=692825,83=434253,107=ZCZ4,269=1,270=453,271=51,273=224500000,336=0,346=17,1023=1,10=239")

unlist(lapply(strsplit(x, ","), function(x) 
    paste(x[grep("(48=\d+|34=\d+)", x)], collapse = ",")));
#[1] "34=4846318,34=20140107,48=637548,48=637548,48=637548,34=585592"
#[2] "34=4846344,48=772825,48=692825,48=692007,48=35213,48=692825"

Answer 2

您还可以使用 (?<=,|^)(?:48|34)=[^,]* 等 PCRE 正则表达式提取所需的值，然后 sapply 找到的匹配项 collapse 使用 , 构建最终的结果：

x <- c("1128=9,9=282,35=X,34=4846318,52=20140107224500037,34=20140107,268=3,279=0,22=8,48=637548,83=585590,107=ZCH4,269=4,270=425,273=224500000,286=5,279=0,22=8,48=637548,83=585591,107=ZCH4,269=E,273=425.5,273=224500000,279=0,273=8,48=637548,34=585592,107=ZCH4,269=F,270=425,271=100,273=224500000,10=144", "1128=9,9=467,35=X,34=4846344,52=20140107224500107,75=20140108,268=5,279=0,22=8,48=772825,279=0,22=8,48=692825,83=434250,107=ZCZ4,269=E,270=453,271=41,273=224500000,279=0,22=8,48=692007,83=434251,107=ZCZ4,269=F,270=452.75,273=224500000,279=0,22=8,48=35213,83=434252274=2,336=0,451=0.25,279=1,22=8,48=692825,83=434253,107=ZCZ4,269=1,270=453,271=51,273=224500000,336=0,346=17,1023=1,10=239")
m <- regmatches(x, gregexpr("(?<=,|^)(?:48|34)=[^,]*", x, perl=TRUE))
sapply(m, function(x) paste(x, collapse=","))
# => [1] "34=4846318,34=20140107,48=637548,48=637548,48=637548,34=585592"
# => [2] "34=4846344,48=772825,48=692825,48=692007,48=35213,48=692825"

见R demo online

图案详情

(?<=,|^) - 在当前位置的左侧必须有一个 , 或字符串的开头（这是一个积极的后视结构，这就是为什么 perl=TRUE 需要gregexpr 将提取输入中的所有匹配项)
(?:48|34) - 48 或 34
= - 等号
[^,]* - ,.

匹配并提取 r 中的子字符串

match and extract substrings in r

regex

string

r

stringr