R devel - Jun 2024 - write.csv problems

Hello, All:


	  I'm getting strange errors with write.csv with some objects of class 
c('findFn', 'data.frame'). Consider the following:


df1 <- data.frame(x=1)
class(df1) <- c('findFn', 'data.frame')
write.csv(df1, 'df1.csv')
# Error in x$Package : $ operator is invalid for atomic vectors

df2 <- data.frame(a=letters[1:2],
       b=as.POSIXct('2024-06-28'))
class(df2) <- c('findFn', 'data.frame')
write.csv(df2, 'df1.csv')
# Error in tapply(rep(1, nrow(x)), xP, length) :
#  arguments must have same length


	  "write.csv" works with some objects of class c('findFn', 
'data.frame') but not others. I have 'findFn' object with 5264
rows that
fails with the following error:


Error in `[<-.data.frame`(`*tmp*`, needconv, value = list(Count = 
c("83",  :
   replacement element 1 has 526 rows, need 5264


	  I have NOT yet been able to reproduce this error with a smaller 
example. However, starting 'write.csv' with something like the following
should fix all these problems:


if(is.data.frame(x)) class(x) <- 'data.frame'


	  Comments?
	  Thanks for all your work to help improve the quality of statistical 
software available to the world.


	  Spencer Graves

? Fri, 28 Jun 2024 11:02:12 -0500
Spencer Graves <spencer.graves at prodsyse.com> ?????:
> df1 <- data.frame(x=1)
> class(df1) <- c('findFn', 'data.frame')
> write.csv(df1, 'df1.csv')
> # Error in x$Package : $ operator is invalid for atomic vectors
Judging by the traceback, only data frames that have a Package column
should have a findFn class:

9: PackageSummary(xi)
8: `[.findFn`(x, needconv)
7: x[needconv]
6: lapply(x[needconv], as.character)
5: utils::write.table(df1, "df1.csv", col.names = NA, sep =
",",
       dec = ".", qmethod = "double")

write.table sees columns that aren't of type character yet and tries to
convert them one by one, subsetting the data frame as a list. The call
lands in sos:::`[.findFn`

    if (missing(j)) {
        xi <- x[i, ]
        attr(xi, "PackageSummary") <- PackageSummary(xi)
        class(xi) <- c("findFn", "data.frame")
        return(xi)
    }

Subsetting methods are hard. For complex structures like data.frames,
`[.class` must handle all of x[rows,cols]; x[rows,]; x[,cols];
x[columns]; x[], and also respect the drop argument:
https://stat.ethz.ch/pipermail/r-help/2021-December/473207.html

I think that the `[.findFn` method mistakes x[needconv] for
x[needconv,] when it should instead perform x[,needconv].

-- 
Best regards,
Ivan

?s 17:02 de 28/06/2024, Spencer Graves escreveu:
> Hello, All:
> 
> 
>  ????? I'm getting strange errors with write.csv with some objects of 
> class c('findFn', 'data.frame'). Consider the following:
> 
> 
> df1 <- data.frame(x=1)
> class(df1) <- c('findFn', 'data.frame')
> write.csv(df1, 'df1.csv')
> # Error in x$Package : $ operator is invalid for atomic vectors
> 
> df2 <- data.frame(a=letters[1:2],
>  ????? b=as.POSIXct('2024-06-28'))
> class(df2) <- c('findFn', 'data.frame')
> write.csv(df2, 'df1.csv')
> # Error in tapply(rep(1, nrow(x)), xP, length) :
> #? arguments must have same length
> 
> 
>  ????? "write.csv" works with some objects of class
c('findFn',
> 'data.frame') but not others. I have 'findFn' object with
5264 rows that
> fails with the following error:
> 
> 
> Error in `[<-.data.frame`(`*tmp*`, needconv, value = list(Count = 
> c("83",? :
>  ? replacement element 1 has 526 rows, need 5264
> 
> 
>  ????? I have NOT yet been able to reproduce this error with a smaller 
> example. However, starting 'write.csv' with something like the
following
> should fix all these problems:
> 
> 
> if(is.data.frame(x)) class(x) <- 'data.frame'
> 
> 
>  ????? Comments?
>  ????? Thanks for all your work to help improve the quality of 
> statistical software available to the world.
> 
> 
>  ????? Spencer Graves
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
Hello,

I don't know if this answers to question.
I wasn't able to reproduce errors but warnings, yes I was.

A way of not giving errors or warnings is to call write.csv at the end 
of a pipe such as the following.


df1 <- findFn("mean")
df1 |> as.data.frame() |> write.csv("df1.csv")


This solution is equivalent to the code proposed in the OP without the 
need for a change in base R.

Hope this helps,

Rui Barradas


-- 
Este e-mail foi analisado pelo software antiv?rus AVG para verificar a presen?a
de v?rus.
www.avg.com