R CMD check fails with dev version of tidyr about radiant

[vnijs]

@hadley Thanks for checking how changes to tidyr will affect others! Really appreciated.

The tab below used to gather fine but doesn't with the new tidyr. For 4/5 cases I switched to as.data.frame as that seems simpler and gives me what I need (and is not likely to change any time soon :)).

More interesting, perhaps, is the segfault I ran into (see second block below).

tab <- structure(c(39.1067931038135, 63.5264195668282, 32.4450680955929, 
52.704884372479), class = "table", .Dim = c(2L, 2L), .Dimnames = structure(list(
    c("Low Income", "High Income"), c("WS Journal", "USA Today"
    )), .Names = c("", "")))

tab %>% data.frame(., check.names = FALSE)

I had been using gather_ and as I was trying to figure out what was going on and trying to drop a variable I got segfault in R-gui on mac (3.2.2) running the code below:

tab <- structure(c(162.787931034483, 100.212068965517, 196.212068965517, 
120.787931034483), .Dim = c(2L, 2L), .Dimnames = structure(list(
    c("Low Income", "High Income"), c("WS Journal", "USA Today"
    )), .Names = c("", "")))

tab %>% 
  data.frame(., check.names = FALSE) %>%
  mutate(rnames = rownames(.)) %>% 
  gather_(., "variable", "values", -which(colnames(.) == "rnames"))

[hadley]

This works:

tab %>% 
  gather(variable, values, -rnames)

so I think something is wrong with your column spec, and tidyr isn't doing a good job of warning. Let me look more

[hadley]

Ok, now I get: Error: Unknown column names: -3.

You need:

tab %>% 
  data.frame(., check.names = FALSE) %>%
  mutate(rnames = rownames(.)) %>% 
  gather_(., "variable", "values", setdiff(colnames(.), "rnames")))

[vnijs]

Hadn't thought about setdiff. Nice. Could a setdiff example perhaps be added to the documentation for gather_? Similarly, something like the below would be a nice add-on for the dplyr::select_ documentation. Thanks @hadley

select_(iris, .dots = setdiff(colnames(iris), c("Petal.Length", "Petal.Width")))