r keeping 0.0 when using paste or paste0

问题

This is a simple question but it is starting to annoy me that I cant find a solution....

I would like to be able to keep the 0.0 when using it as an output when using paste or paste0 so if i have the following:

y <- c(-1.5,-1.0,-0.5,0.0,0.5,1.0,1.5)
> y
[1] -1.5 -1.0 -0.5  0.0  0.5  1.0  1.5
paste0("x",y,"x")

I get:

[1] "x-1.5x" "x-1x"   "x-0.5x" "x0x"    "x0.5x"  "x1x"    "x1.5x" 

but want:

[1] "x-1.5x" "x-1.0x"   "x-0.5x" "x0.0x"    "x0.5x"  "x1.0x"    "x1.5x" 

回答1:

You can use sprintf():

paste0("x", sprintf("%.1f", y), "x")

回答2:

There's also formatC:

paste0("x", formatC(y, digits = 1, format = "f"), "x")

回答3:

There is also format and drop0trailing

paste0('x',format(y,drop0Trailing = F),'x')

And, if you really want only 0 replaced with 0.0, not (1.0 or -1.0) then

paste0('x',gsub(x = gsub(x = format(y, drop0trailing = T),'0$', '0.0'),' ',''),'x')
## [1] "x-1.5x" "x-1x"   "x-0.5x" "x0.0x"  "x0.5x"  "x1x"    "x1.5x" 

Or, as @mrdwab suggested (and is less typying)

paste0('x',gsub("^0$", "0.0", as.character(y)),'x')

来源：https://stackoverflow.com/questions/12243071/r-keeping-0-0-when-using-paste-or-paste0