segmentation fault when unlisting in-place list column

[fklirono]

reproducible example:

dt<-data.table(a=list(1:2, 1:3))
dt[, a:=unlist(a)]
dt

data.table version: 1.12.8

session info:

R version 3.6.2 (2019-12-12)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 16.04.6 LTS

Matrix products: default
BLAS:   /usr/lib/openblas-base/libblas.so.3
LAPACK: /usr/lib/libopenblasp-r0.2.18.so

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8     LC_MONETARY=en_US.UTF-8   
 [6] LC_MESSAGES=en_US.UTF-8    LC_PAPER=en_US.UTF-8       LC_NAME=C                  LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] data.table_1.12.8 colorout_1.2-0    rmarkdown_2.0    

loaded via a namespace (and not attached):
[1] compiler_3.6.2  tools_3.6.2     htmltools_0.4.0 Rcpp_1.0.3      knitr_1.26      xfun_0.11       digest_0.6.23   rlang_0.4.2     evaluate_0.14  

[jangorecki]

thank you for reporting, I can reproduce on recent devel

[MichaelChirico]

Hmm it doesn't segfault for me, but the table is clearly broken (or at least, did the wrong thing):

dput(dt)
# structure(list(a = list(c(1L, 2L, 1L, 2L, 3L), c(1L, 2L, 1L, 2L, 3L))), row.names = c(NA, -2L), class = c("data.table", "data.frame"), .internal.selfref = <pointer: 0x7f936e0044e0>)

[D3SL]

I think I ran into the same issue. I found a workaround using the unnest_dt2 function from here. For anyone else looking to do the same be sure not to use unnest_dt, it mangles numbers so coercing back to integer/numeric results in a column full of NAs.

Reproducible example:

library(data.table)
testdata<-data.frame(start=seq(30001,80001,10000),end=seq(40000,90000,10000))
testdata<-as.data.table(testdata)
testdata[,range:=list(list(start:end)),by=1:nrow(testdata)]
testdata[,range:=unlist(range)]

sessioninfo:
data.table version: 1.12.8

R version 3.6.3 (2020-02-29)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 18362)

Matrix products: default

locale:
[1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United States.1252   
[3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C                          
[5] LC_TIME=English_United States.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] reprex_0.3.0

loaded via a namespace (and not attached):
 [1] Rcpp_1.0.1      ps_1.3.0        digest_0.6.20   R6_2.4.1        evaluate_0.14   rlang_0.4.5    
 [7] fs_1.3.1        callr_3.4.3     whisker_0.4     rmarkdown_2.1   tools_3.6.3     xfun_0.13      
[13] compiler_3.6.3  processx_3.4.0  clipr_0.7.0     htmltools_0.3.6 knitr_1.28