Convert all character variables in your data.frame to factors

df.make.factors <- function(df)
{ 
    ## Purpose: Convert all character variables in your data.frame to factors 
    ## Arguments:
    ##   df: a data frame
    ## Return: a data frame with converted factors on those character variables.
    ## Author: Feiming Chen, Date: 17 Oct 2017, 14:26
    ## ________________________________________________

    character_vars <- sapply(df, class) == "character"
    df[, character_vars] <- lapply(df[, character_vars], factor)
    df
}
if (F) {                                # Unit Test
    df <- data.frame(x=c("x", "x", "y"), y=1:3, z=c("1", "3", "3"))
    df.make.factors(df)
}

Display a (numeric) vector in a pretty format

display.vector <- function(x)
{ 
    ## Purpose: Display a vector in a pretty format
    ## Arguments:
    ##   x: a vector
    ## Return: a png picture for the vector. (each row has 10 elements)
    ## Author: Feiming Chen, Date:  2 Oct 2017, 14:54
    ## ________________________________________________

    N <- length(x)
    n1 <- N %% 10
    if (n1 > 0) {
        n2 <- 10 - n1
        x.add <- rep(NA, n2)
        x <- c(x, x.add)
    }

    x1 <- matrix(x, ncol = 10, byrow = T)
    n2 <- nrow(x1)
    nr <- paste0(10 * (seq.int(n2) - 1) + 1, ": ")
    dimnames(x1) <- list(nr, 1:10)

    tex.print(x1)
}
if (F) {                                # Unit Test
    x <- c(402.6615584,402.1343365,402.5467634,401.835917,402.9268321,404.5185276,406.0735012,408.7713965,408.2033098,411.043676,413.953578,420.6021333,426.6352944,440.9007592,471.5614004,523.8426555,619.173643,782.3175971,1033.289048,1321.267143,1615.935774,1898.979548,2173.03472,2442.864835,2682.25644,2884.575978,3064.278857,3252.58248,3413.084683,3588.447246,3701.244129,3796.824264,3840.251429,3943.184319,4084.131835,4037.30822,4116.338229,4191.71438,4173.699815,4110.847391,4197.181334,4221.081422,4207.343855,4209.140892,4263.463393,4306.872737,4312.087451,4269.522631,4313.924265,4265.306511) 
    display.vector(x)
}

tex.print <- function(x, type=c("PNG", "HTML"), file=NULL, caption = file, digits=0, ...) {
    ## Purpose: Generate HTML or PNG representation of a data/table/model object.
    ##          Require R "memisc" package. 
    ## Arguments:
    ##   x: an object (table, ftable, data frame, model object, etc. that are acceptable in R "memisc" package.
    ##   type: what to generate -- 
    ##         "HTML" shows a HTML table in a web browser. 
    ##         "PNG" shows a PNG (image) file (require linux commands: latex, dvipng, display).
    ##   file: make a copy of the PNG file with this name.  Also used for the table name.
    ##   caption: table caption. 
    ##   digits: number of decimal places to use. 
    ##    ...: passed to "toLatex"
    ## Return: Display the data representation and an image file (type="PNG") for insertion. 
    ## Author: Feiming Chen, Date: 14 Feb 2017, 11:59
    ## ________________________________________________

    require(memisc)
    type <- match.arg(type)
    
    switch(type,
           HTML = {
               ## Show HTML table in a Web Browser
               memisc::show_html(x)      
           }, 
           PNG = {
               ## Generate LaTeX and PNG Image file
               r <- toLatex(x, ..., digits=digits, show.vars=TRUE)
               f <- file("X.tex", "w")
               writeLines(c("\\documentclass{article}",
                            "\\usepackage{booktabs}",
                            "\\usepackage{dcolumn}",
                            "\\begin{document}", 
                            "\\pagenumbering{gobble}"), f)
               if (!is.null(file)) writeLines("\\begin{table}  \\centering", f)

               writeLines(r, f)

               if (!is.null(caption)) {
                   writeLines(paste0("\\caption{", caption, "} \\end{table}"), f)
               }

               writeLines("\\end{document}", f)
               close(f)

               system("latex X.tex >/dev/null") # Generate DVI file from LaTeX file (X.tex -=> X.dvi)
               system("dvipng -q* -o X.png -T tight -D 200 X.dvi >/dev/null") # convert to PNG file with Tight box and Resolution of 200
               system("display X.png &")                                     # display the PNG file. 
               file.remove("X.tex", "X.log", "X.aux", "X.dvi")

               if (!is.null(file)) file.copy("X.png", paste0(file,".png"), overwrite = T) 
               if (!grepl("/tmp", getwd())) {
                   file.copy("X.png", "~/tmp/X.png", overwrite = T)
               }
           }
           )
    invisible(NULL)
}