Sorry - I figured that this to be a more common defined error than anything specific to the data/function... Thanks for looking at this.
The data and function are below. Creating a single line of the data.frame at a time will work (i.e. fold(s)) For multiple line data.frames, an error is generated. Ideally I would like to record the output from fold(sq) in a two column data.frame, whether it requires reading in the data to fold one line at a time or in bulk. > library(GeneRfold) > s<- "ATTATGCATCGACTAGCATCACTAG" > fold(s) [[1]] [1] "...((((........))))......" [[2]] [1] -2.3 > sq <- data.frame(c("ATGTGTGATATGCATGTACAGCATCGAC", + "ACTAGCACTAGCATCAGCTGTAGATAGA", + "ACTAGCATCGACATCATCGACATGATAG", + "CATCGACTACGACTACGTAGATAGATAG", + "ATCAGCACTACGACACATAGATAGAATA")) >fold(sq) Error in fold(sq) : STRING_ELT() can only be applied to a 'character vector', not a 'list' > struct <- t(as.data.frame(sapply(sq[,1], fold, t=37))) Error in FUN(X[[1L]], ...) : STRING_ELT() can only be applied to a 'character vector', not a 'integer' >dput(fold,file="fred123") function (s, t = 37) { .Call("foldR", s, t, PACKAGE = "GeneRfold") } > dput(sq) structure(list(c..ATGTGTGATATGCATGTACAGCATCGAC....ACTAGCACTAGCATCAGCTGTAGATAGA... = structure(c(4L, 1L, 2L, 5L, 3L), .Label = c("ACTAGCACTAGCATCAGCTGTAGATAGA", "ACTAGCATCGACATCATCGACATGATAG", "ATCAGCACTACGACACATAGATAGAATA", "ATGTGTGATATGCATGTACAGCATCGAC", "CATCGACTACGACTACGTAGATAGATAG"), class = "factor")), .Names = "c..ATGTGTGATATGCATGTACAGCATCGAC....ACTAGCACTAGCATCAGCTGTAGATAGA...", row.names = c(NA, -5L), class = "data.frame") > dput(s) "ATTATGCATCGACTAGCATCACTAG" > sessionInfo() R version 2.11.0 (2010-04-22) i386-apple-darwin9.8.0 locale: [1] en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8 attached base packages: [1] stats graphics grDevices utils datasets methods base other attached packages: [1] GeneRfold_1.6.0 GeneR_2.18.0 loaded via a namespace (and not attached): [1] tools_2.11.0 -- View this message in context: http://r.789695.n4.nabble.com/Error-in-FUN-X-1L-STRING-ELT-can-only-be-applied-to-a-character-vector-not-a-integer-tp2226811p2227512.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.