Unrecognized escaped in keyby

[HughParsonage]

library(data.table)
DT <- data.table(x = 1, y = 1:5)
setnames(DT, "x", "\\phantom{.}")
DT[, .(y = mean(y)), keyby = "\\phantom{.}"]
#> Error: '\p' is an unrecognized escape in character string starting "`\p"

Of course, I can change to keyby = `\\phantom{.}` , but that can be hard to know in advance.

^{Created on 2019-01-27 by the reprex package (v0.2.1)}

Session info

devtools::session_info()
#> - Session info ----------------------------------------------------------
#>  setting  value                       
#>  version  R version 3.5.2 (2018-12-20)
#>  os       Windows 10 x64              
#>  system   x86_64, mingw32             
#>  ui       RTerm                       
#>  language (EN)                        
#>  collate  English_Australia.1252      
#>  ctype    English_Australia.1252      
#>  tz       Australia/Sydney            
#>  date     2019-01-27                  
#> 
#> - Packages --------------------------------------------------------------
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#> 
#> [1] C:/R/R-3.5.2/library
#> [2] C:/R/R-3.5.1/library

[jangorecki]

Instead of dealing with that particular I would prefer to provide a helper function for cleaning up column names, and ask people to use that in such cases.

[DavidArenburg]

We could add check.names argument to setnames (like we have in setDT or fread)

[sritchie73]

The "\" character is always treated as an escape key (using the following character) in strings (even when writing markdown comments here!). So if you want an actual backslash, you need to escape each backslash:

> DT[, .(y = mean(y)), keyby = "\\\\phantom{.}"]
   \\phantom{.} y
1:            1 3

[HughParsonage]

@sritchie73 That's not quite true.

DT <- data.table(x = 1)
setnames(DT, "\n")
DT[, .(a = 1), keyby = "\n"]
#    \n a
# 1:  1 1