Off topic:Error in as.vector(x) : no method for coercing this S4 class to a vector

Question

[pr2009]

I tried to run the following code in R studio. Everything worked fine, except at the last step [write.table(mdat, "recount_mdat.csv")] when I tried to export the 'mdat', I got the following error:

 Error in as.vector(x) : no method for coercing this S4 class to a vector

My code

 library('dplyr')
 library('recount')
 library('magrittr')
 library('ffpe')
 library('RSkittleBrewer')
 library('SummarizedExperiment')
 library('devtools')
 trop <- RSkittleBrewer::RSkittleBrewer('tropical')
 colon_proj <- c('SRP025982', 'SRP42161')
 if(any(!file.exists(file.path(colon_proj, 'rse_gene.Rdata')))) {
 sapply(colon_proj, download_study)
 }

 blood_proj <- c('SRP066834', 'SRP041736', 'SRP060416')
 if(any(!file.exists(file.path(blood_proj, 'rse_gene.Rdata')))) {
 sapply(blood_proj, download_study)
 }
 proj <- c(colon_proj,blood_proj)

 dat <- lapply(proj, function(x) {
 load(file.path(x, 'rse_gene.Rdata'))
 return(rse_gene)
 })
 proj

 sapply(dat, dim)

 metadata <- all_metadata('sra')

 write.table(metadata, "recount_metadata.csv")

 mdat <- do.call(cbind, dat)

 write.table(mdat, "recount_mdat.csv")