Error in re-building vignettes:
  ...
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  The vignette engine knitr::rmarkdown is not available, because the rmarkdown package is not installed. Please install it.
Warning in .which.datatype(stname2code(names(demogt)[i]))(demogt[[i]]) :
  NAs introduced by coercion
Warning in .which.datatype(stname2code(names(demogt)[i]))(demogt[[i]]) :
  NAs introduced by coercion
Warning in .which.datatype(stname2code(names(demogt)[i]))(demogt[[i]]) :
  NAs introduced by coercion
Warning in .which.datatype(stname2code(names(demogt)[i]))(demogt[[i]]) :
  NAs introduced by coercion
Warning in .which.datatype(stname2code(names(demogt)[i]))(demogt[[i]]) :
  NAs introduced by coercion
Warning in `[.data.table`(demogt, , `:=`("index", seq(nrow(demogt)))) :
  Invalid .internal.selfref detected and fixed by taking a (shallow) copy of the data.table so that := can add this new column by reference. At an earlier point, this data.table has been copied by R (or been created manually using structure() or similar). Avoid key<-, names<- and attr<- which in R currently (and oddly) may copy the whole data.table. Use set* syntax instead to avoid copying: ?set, ?setnames and ?setattr. Also, in R<=v3.0.2, list(DT1,DT2) copied the entire DT1 and DT2 (R's list() used to copy named objects); please upgrade to R>v3.0.2 if that is biting. If this message doesn't help, please report to data.table issue tracker so the root cause can be fixed.
Warning: Removed 4 rows containing missing values (geom_vline).
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  The vignette engine knitr::rmarkdown is not available, because the rmarkdown package is not installed. Please install it.
Warning in .which.datatype(stname2code(names(demogt)[i]))(demogt[[i]]) :
  NAs introduced by coercion
Warning in .which.datatype(stname2code(names(demogt)[i]))(demogt[[i]]) :
  NAs introduced by coercion
Warning in .which.datatype(stname2code(names(demogt)[i]))(demogt[[i]]) :
  NAs introduced by coercion
Warning in .which.datatype(stname2code(names(demogt)[i]))(demogt[[i]]) :
  NAs introduced by coercion
Warning in .which.datatype(stname2code(names(demogt)[i]))(demogt[[i]]) :
  NAs introduced by coercion
Warning in `[.data.table`(demogt, , `:=`("index", seq(nrow(demogt)))) :
  Invalid .internal.selfref detected and fixed by taking a (shallow) copy of the data.table so that := can add this new column by reference. At an earlier point, this data.table has been copied by R (or been created manually using structure() or similar). Avoid key<-, names<- and attr<- which in R currently (and oddly) may copy the whole data.table. Use set* syntax instead to avoid copying: ?set, ?setnames and ?setattr. Also, in R<=v3.0.2, list(DT1,DT2) copied the entire DT1 and DT2 (R's list() used to copy named objects); please upgrade to R>v3.0.2 if that is biting. If this message doesn't help, please report to data.table issue tracker so the root cause can be fixed.
Quitting from lines 111-114 (data_clean.Rmd) 
Error: processing vignette 'data_clean.Rmd' failed with diagnostics:
SETLENGTH() cannot be applied to an ALTVEC object.
Execution halted