R grep & gsub issue - sign seems to be causing an issue...

I would like to use grep and gsub to manipulate a vector to make the names used consistent, i.e. reduce a level or two.  
  

However, here is what I found when I attempted to use grep and gsub:
   
  

tmp_test<-c("House 1 Plot Plus +100","House 2 Plot Plus +100","House 3 Plot Plus -100","House 4 Plot Plus -100","House 1 Plus +100","House 2 Plus +100","House 3 Plus -100","House 4 Plus -100")
    

gsub(tmp_test[2], tmp_test[1], tmp_test)
    

[1] "House 1 Plot Plus +100" "House 2 Plot Plus +100" "House 3 Plot Plus -100" "House 4 Plot Plus -100" "House 1 Plus +100"      "House 2 Plus +100"     
[7] "House 3 Plus -100"      "House 4 Plus -100"     

  

grep(tmp_test[1],tmp_test)
    

integer(0)

However, 
  

gsub(tmp_test[3], tmp_test[1], tmp_test)
    

[1] "House 1 Plot Plus +100" "House 2 Plot Plus +100" "House 1 Plot Plus +100" "House 4 Plot Plus -100" "House 1 Plus +100"      "House 2 Plus +100"     
[7] "House 3 Plus -100"      "House 4 Plus -100"

Thanks for any feedback that can be provided.

Jason Rupert wrote:

I would like to use grep and gsub to manipulate a vector to make the names 
used consistent, i.e. reduce a level or two. 

This is dangerous:  grep and gsub use regular expressions, so a lot of 
characters (see ?regexp for the list) have special meanings.

For the kind of substitutions you want, just do things like

newlist <- tmp_test
newlist[newlist == tmp_test[2]] <- tmp_test[1]

Duncan Murdoch

However, here is what I found when I attempted to use grep and gsub:

tmp_test<-c("House 1 Plot Plus +100","House 2 Plot Plus +100","House 3 
Plot Plus -100","House 4 Plot Plus -100","House 1 Plus +100","House 2 Plus 
+100","House 3 Plus -100","House 4 Plus -100")

gsub(tmp_test[2], tmp_test[1], tmp_test)

[1] "House 1 Plot Plus +100" "House 2 Plot Plus +100" "House 3 Plot Plus 
-100" "House 4 Plot Plus -100" "House 1 Plus +100"      "House 2 Plus +100" 
[7] "House 3 Plus -100"      "House 4 Plus -100"

grep(tmp_test[1],tmp_test)

integer(0)

However, 

gsub(tmp_test[3], tmp_test[1], tmp_test)

[1] "House 1 Plot Plus +100" "House 2 Plot Plus +100" "House 1 Plot Plus 
+100" "House 4 Plot Plus -100" "House 1 Plus +100"      "House 2 Plus +100" 
[7] "House 3 Plus -100"      "House 4 Plus -100"

Thanks for any feedback that can be provided.