[R] saveRDS() and readRDS() Why? [solved, pretty much anyway)

[William Dunlap]

You wrote:
  ## On Windows 3.4.2

>   x <- airquality
>   saveRDS(x, file = "x.rds")
>   saveRDS(x, file = "y.rds")
>

  Files x.rds and y.rds are identical in size but utterly different in
content.

Wow!  Can you show us the results of
  x <- datasets::airquality
  saveRDS(x, file="x.rds")
  saveRDS(x, file="y.rds")
  tools::md5sum(c("x.rds", "y.rds"))
  dput(readBin("x.rds", what="raw", n=file.size("x.rds")))
  dput(readBin("y.rds", what="raw", n=file.size("y.rds")))

(Copy and paste, as text, from the R session, so we can see the input and
the output in context.





Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Mon, Nov 12, 2018 at 12:42 PM, p_connolly <p_connolly using slingshot.co.nz>
wrote:

> On 2018-11-12 22:49, peter dalgaard wrote:
>
>> Er, where, what, how? I can't reproduce that, at least not on 3.5.1 on
>> MacOS:
>>
>> x <- airquality
>>> saveRDS(x, file = "x.rds")
>>> x <- NULL
>>> x <- readRDS(file = "x.rds")
>>> x
>>>
>>     Ozone Solar.R Wind Temp Month Day
>> 1      41     190  7.4   67     5   1
>> 2      36     118  8.0   72     5   2
>> 3      12     149 12.6   74     5   3
>> ...
>>
>> Looks fine to me.
>>
>>
> It seems to work fine using the same installation to read as used for the
> save.
> But it's a different story if the save was done on a Windows installation
> and read on a Linux installation.
>
> ## On Windows 3.4.2
>
>> x <- airquality
>> saveRDS(x, file = "x.rds")
>> saveRDS(x, file = "y.rds")
>>
>
> Files x.rds and y.rds are identical in size but utterly different in
> content.
>
> ## On Linux 3.5.1
>
> x <- readRDS(file =  "x.rds")
>>
> Error in readRDS(file = "x.rds") : error reading from connection
>
>> x <- readRDS(file =  "y.rds")
>> head(x)
>>
>   Ozone Solar.R Wind Temp Month Day
> 1    41     190  7.4   67     5   1
> 2    36     118  8.0   72     5   2
> 3    12     149 12.6   74     5   3
> 4    18     313 11.5   62     5   4
> 5    NA      NA 14.3   56     5   5
> 6    28      NA 14.9   66     5   6
>
> It might just be the age of the Windows installation.  I don't have much
> use for Windows, so I haven't had much inclination to install a newer
> version.
>
> YMMV
>
>
>
> ?
>> -pd
>>
>>
>> On 12 Nov 2018, at 08:28 , Patrick Connolly <p_connolly using slingshot.co.nz>
>>> wrote:
>>>
>>> The solution was very simple.  Don't use the same name for the rds
>>> file  as used for the R object, viz a vie:
>>>
>>> saveRDS(x, file = "x.rds")
>>> and
>>> x <- readRDS(file = "x.rds")
>>>
>>> will not work; however
>>>
>>> saveRDS(x, file = "y.rds")
>>> and
>>> x <- readRDS(file = "y.rds")
>>> will work.
>>>
>>> An undocumented feature?
>>>
>>> Thanks to all who contributed.
>>>
>>
>> --
>> Peter Dalgaard, Professor,
>> Center for Statistics, Copenhagen Business School
>> Solbjerg Plads 3, 2000 Frederiksberg, Denmark
>> Phone: (+45)38153501
>> Office: A 4.23
>> Email: pd.mes using cbs.dk  Priv: PDalgd using gmail.com
>>
>
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