I have a set of words like this one:

```
ctr_names <- c("Czech_Republic","New_Zealand","Great_Britain", "Spain", "France")

```

I want to RETAIN JUST words with "\_" characters and remove the rest of words. I wish a final result as:

```
[1] "Czech_Republic" "New_Zealand"    "Great_Britain" 

```

I've been trying with 

```
gsub("[_]", " ", ctr_names)

```

but it does not work because it remove the character I wanna retain. Any help will be appreciated