print(dt, class=TRUE) shows only "topn - 1" rows

[heavywatal]

When class=TRUE is provided to print.data.table(), only topn - 1 rows are printed. Is this a bug, or a feature? If the former is the case, as I suppose, the flaw seems to be in the line 87 of print.data.table.R.

Minimal example:

library(data.table)
print(as.data.table(iris), topn=3L, class=TRUE)
#      Sepal.Length Sepal.Width Petal.Length Petal.Width   Species
#             <num>       <num>        <num>       <num>    <fctr>
#   1:          5.1         3.5          1.4         0.2    setosa
#   2:          4.9         3.0          1.4         0.2    setosa
#  ---
# 148:          6.5         3.0          5.2         2.0 virginica
# 149:          6.2         3.4          5.4         2.3 virginica
# 150:          5.9         3.0          5.1         1.8 virginica

sessionInfo()

R version 3.5.0 (2018-04-23)
Platform: x86_64-apple-darwin15.6.0 (64-bit)
Running under: macOS High Sierra 10.13.4

Matrix products: default
BLAS: /Library/Frameworks/R.framework/Versions/3.5/Resources/lib/libRblas.0.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/3.5/Resources/lib/libRlapack.dylib

locale:
[1] C/en_US.UTF-8/C/C/C/C

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

other attached packages:
[1] data.table_1.10.4-3

loaded via a namespace (and not attached):
[1] compiler_3.5.0

Thanks.

[MichaelChirico]

That's a bug! Probably my fault. Since you've already identified the problem, feel free to file a PR. If not, I'll fix this soon.

[heavywatal]

Confirmed. Thank you for your prompt response, @MichaelChirico and @mattdowle !