Function to require a R package and install it if needed.

require.install.package.R

require.install <- function(pkg, github=""){
  req <- suppressWarnings(
            suppressMessages(
              require(package=paste(pkg), character.only=TRUE)
              )
            );
  #print(github);
  if(!req){
    installOk <- FALSE;
    if(length(github)<=0){
      suppressWarnings(
        suppressMessages(
          install.packages(paste(pkg),dep=TRUE)
          )
        );
      installOk <- TRUE;
    }else if(length(github)>0){
      if(suppressWarnings(
          suppressMessages(
            require("devtools")
            )
          )
         ){
              suppressWarnings(
                suppressMessages(
                  install_github(paste(pkg),paste(github))
                  )
                );
              installOk <- TRUE;
      }
    }
    
    if(installOk){
      suppressWarnings(
        suppressMessages(
          require(package=paste(pkg), character.only=TRUE)
          )
        );
    }
    
  }
}