Removing white spaces after specific symbol ";"

I have a question regarding removing white spaces within a character text inside a column data frame. This is my data frame column:

head(data$HO)
[1] "Lidar; Wind field; Temperature; Aerosol; Fabry-Perot etalon"                             
[2] "Compressive ghost imaging; Guided filter; Single-pixel imaging"

This question differs from this one link as I want to remove only the spaces after the symbol ";" , so the output should look like this:

head(data$HO)
[1] "Lidar;Wind field;Temperature;Aerosol;Fabry-Perot etalon"                             
[2] "Compressive ghost imaging;Guided filter;Single-pixel imaging"

I have tried

data$HO <- gsub("\\;s", ";",data$HO)

but it doesn't work.

Any suggestion?

Solution

You may use ;\s+ pattern and replace with ;:

> x <- c("Lidar; Wind field; Temperature; Aerosol; Fabry-Perot etalon", "Compressive ghost imaging; Guided filter; Single-pixel imaging")
> gsub(";\\s+", ";", x)
[1] "Lidar;Wind field;Temperature;Aerosol;Fabry-Perot etalon"     
[2] "Compressive ghost imaging;Guided filter;Single-pixel imaging"

Pattern details:

; - a semi-colon
\s+ - one or more whitespace chars.

See the regex demo.

Some more variations of the solution:

gsub("(*UCP);\\K\\s+", "", x, perl=TRUE)
gsub(";[[:space:]]+", ";", x)