限制R中特定单词后的字符长度

Question

I have vector of names that I would like to clean. I would like to shorten each character length:

Example:

x <- c("LambMa, a.b.c., LaMa (shorter wording), LambM, abc , a.b.c",
       "LambMa, a.b.c., LaMa (shorter wording)") 

I would like to obtain in this example only the first LambMa abc and cut off the rest. So if the specific character doesn't contain the abc twice DO NOTHING (skip).

So the specific word or expression to look for is "abc" . so cut the rest after first occurrence.

EDIT: I would like to obtain only the characters before abc (included) from vector x in case the there is double occurrence of abc in that given character string x .

The solution to the example above would be:

solution <- c("LambMa, a.b.c.","LambMa, a.b.c., LaMa (shorter wording)") 

EDIT 2: Also partial solution would be very helpful and would be accepted. Thanks

Answer 1

x <- c("LambMa, a.b.c., LaMa (shorter wording), LambM, abc , a.b.c",
       "LambMa, a.b.c., LaMa (shorter wording)") 

occ_abc<-gregexpr("a.b.c",x) # find the occurences of "a.b.c."
for(i in 1:length(occ_abc)){ # for each item of x
    if(length(occ_abc[[i]])>=2) { # if there is 2 or more occurences
      x[i]<-substr(x[i],1,occ_abc[[i]][1]+5) # replace with first part of the string
    } else { # else leave the item untouched
      x[i]
    }
}

>x

[1] "LambMa, a.b.c."                         "LambMa, a.b.c., LaMa (shorter wording)"

The if...else part can very probably be replaced by an ifelse statement.

Answer 2

You can use gsub to swap out if the pattern you specified matches. To avoid using a look-behind, you can capture the first abc and replace with it:

gsub("(a\\.b\\.c\\.).+(a\\.b\\.c)","\\1",x)
[1] "LambMa, a.b.c."                        
[2] "LambMa, a.b.c., LaMa (shorter wording)"