this is more a question of interest, as I found a work-around, although I don't find it pretty.
When I updated the pander package (to 0.6.1) an error started to occure whenever I try to to use pander() on a data.table in wide format that was constructed from a data.table (package version 1.10.4-3 or older) in long format using data.table::dcast():
Error in data.table::setattr(x, "row.names", row.names.dt) : row names must be 'character' or 'integer', not 'double'
I tried to remove any row names, but to no avail. After some research, I found out that with reshape2::dcast there is no error, but reshape2::dcast transforms the data.table in a data.frame, which isn't something I want. Of course I could transform the data.frame back into a data.table.
Here is some sample code that produces the error for me:
library(pander)
library(data.table)
dt.long <- data.table(time=c(1, 1, 2, 2), T=c("c", "t", "c", "t"), count=c(10, 15, 15, 20))
pander(dt.long) # this works fine
dt.wide <- dcast(dt.long, time~T, value.var = "count")
row.names(dt.wide) <- NULL # doesn't help
row.names(dt.wide) <- c() # doesn't help either
pander(dt.wide) # produces error
# work-around
library(reshape2)
dt.wide <- dcast(dt.long, time~T, value.var = "count")
pander(dt.wide) # works fine
class(dt.wide) # but this is a data.frame
dt.wide <- data.table(dt.wide) # now it is a data.table again
Is there a simple way to keep the data as data.table and use pander as it worked before?
I use R version 3.3.2, in case this matters.
Thank you in advance!
It is the additional attributes that creates the problem. Set the 'sorted' attr to 'NULL' and it should work
dt.wide <- dcast(dt.long, time~T, value.var = "count")
attr(dt.wide, "sorted") <- NULL
Or use setattr
setattr(dt.wide, 'sorted', NULL)
pander(dt.wide)
#----------------
# time c t
#------ ---- ----
# 1 10 15
# 2 15 20
#----------------