Hi The following code results in an error: ###########> x <- data.frame(x = integer(0), y = integer(0)) > x == xError in matrix(if (is.null(value)) logical() else value, nrow = nr, dimnames = list(rn, : length of 'dimnames' [2] not equal to array extent>########### I would expect that it returns logical(0) as both have the same structure and both are empty, or even TRUE? But definitely not an error. Cheers, Rainer ###########> sessionInfo()R version 3.6.1 (2019-07-05) Platform: x86_64-apple-darwin17.7.0 (64-bit) Running under: macOS High Sierra 10.13.6 Matrix products: default BLAS: /System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libBLAS.dylib LAPACK: /System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libLAPACK.dylib locale: [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8 attached base packages: [1] stats graphics grDevices utils datasets methods base loaded via a namespace (and not attached): [1] compiler_3.6.1 ########### -- Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology, UCT), Dipl. Phys. (Germany) Orcid ID: 0000-0002-7490-0066 Department of Evolutionary Biology and Environmental Studies University of Z?rich Office Y34-J-74 Winterthurerstrasse 190 8075 Z?rich Switzerland Office: +41 (0)44 635 47 64 Cell: +41 (0)78 630 66 57 email: Rainer.Krug at uzh.ch Rainer at krugs.de Skype: RMkrug PGP: 0x0F52F982