How do I remove any string that is not followed by a number?

For example, I am working with a string:

string <- c("sb 221 reeb; ab 1355",
"sb 140; sb 14 c ab 1089",
"sb 1518; sb 1067 l ab 1770",
"ab 60 na; ab 1492",
"ab 442 aramb; ab 724; ab 919",
"sb 511 ab 416 state ab 1532")

df <- data.frame(string)

I would like the string to be:

output<- c("sb 221; ab 1355",
"sb 140; sb 14 ab 1089",
"sb 1518; sb 1067 ab 1770",
"ab 60; ab 1492",
"ab 442; ab 724; ab 919"
"sb 511 ab 416 ab 1532")

output_df <- data.frame(output)

Thank you.

CodePudding user response：

 gsub(" ?[a-z] ((?= \\D)|;)", "\\1", string, perl = TRUE)

[1] "sb 221; ab 1355"          "sb 140; sb 14 ab 1089"   
[3] "sb 1518; sb 1067 ab 1770" "ab 60; ab 1492"          
[5] "ab 442; ab 724; ab 919"   "sb 511 ab 416 ab 1532"