[R] foreign package read.spss() and NA levels

[Uwe Ligges]

On 27.05.2021 12:27, Allen, Justin wrote:
> Hi All,
> 
> Wanted to report what may be a bug or possibly an oversight, but I am unsure, in the "foreign" packages in the read.spss() command, https://cran.r-project.org/web/packages/foreign/index.html. When running the following code,
> 
> input <- read.spss("[.sav file location]", to.data.frame = TRUE)
> str(input)
> 
> The read.spss() seems to be applying addNA() to factors so NA is being set as a level, and there seems to be no way to get read.spss() to bring factors in without doing this. This seems to be a recent change as read.spss() was not doing this as of a few months ago. None of the arguments in read.spss() seem to also stop this behaviour. I am currently on the most recent version of both R and the package, as of 27/05/21, and am using RStudio Version 1.4.1106.

Within R (I do not use RStudio) and even with the most recent R-devel, I see

(sav <- system.file("files", "electric.sav", package = "foreign"))
dat <- read.spss(file=sav, to.data.frame=TRUE)
table(dat$DAYOFWK)

#  SUNDAY   MONDAY  TUESDAY WEDNSDAY THURSDAY   FRIDAY SATURDAY
#      19       11       19       17       15       13       16

table(dat$DAYOFWK, useNA="always")

#  SUNDAY   MONDAY  TUESDAY WEDNSDAY THURSDAY   FRIDAY SATURDAY     <NA>
#      19       11       19       17       15       13       16      130

So exactly what you expected?

If you rather use

dat <- read.spss(file=sav, to.data.frame=TRUE, use.missings=FALSE)

table(dat$DAYOFWK, useNA="always")

you see the NA values are converted to a factor level called "MISSING".

If it is different on your end, pelase try in plain R, tell us the 
version of R / foreign and show an example data file where this happens.

Best,
Uwe Ligges



> 
> Any thoughts?
> 
> Many Thanks,
> 
> Justin Allen
> 
> p.s. your continued maintenance and additions to R and its packages have been infinitely useful in my work and life and thank for that.
> 
> Justin Allen
> Housing Consultant, BRE<https://bregroup.com/>
> T: 07807122647
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