Nassim Haddad nassimhaddad

Here I'll drop ggplot2 tricks ...

Table of Contents:

Super fast group by, code from: http://stackoverflow.com/questions/3685492/r-speeding-up-group-by-operations.
Especially, the id() function could prove very useful in building indices.



	insert_row <- function(existingDF, newrow, r){
	r <- as.numeric(r)
	if (length(newrow) != ncol(existingDF)){
	stop("Length of row doesn't match.")
	}
	if (r == 1){
	existingDF <- rbind(newrow,existingDF)
	} else{

	library(yaml)

	# loads the database shema description
	db_list <- yaml.load_file("sample3.yaml")

	# create the database
	con <- dbConnect(SQLite(), "new_db.sqlite")

	# create the tables one by one
	for (i in 1:length(db_list)){

	data.files <- dir('data')
	for (data.file in data.files)
	{
	filename <- file.path('data', data.file)
	variable.name <- sub('\\.csv$', '', data.file, ignore.case = TRUE, perl = TRUE)
	assign(variable.name, read.csv(filename, header = TRUE, sep = ','))
	}

	# looping through vector ####
	library(inline)

	sign <- signature(x="numeric", n="integer", d="numeric")
	code <- "
	for (int i=1; i < *n; i++) {
	x[i] = x[i-1]*d[0] + x[i];
	}"

	c_fn <- cfunction(sign,

	library(R2HTML)

	# setup a temporaty file to store the code
	fileName <- 'temp.html'
	.HTML.file = file.path(getwd(), fileName)

	# make a title
	HTML(as.title("Title of my report"), append = FALSE)
	# add space
	HTMLhr()

	library(xtable)

	print_df <- function(df){
	print(xtable(df), type = "html", include.rownames = FALSE)
	}

	# tricks with regular expressions ####

	# insert character after a given pattern: use \\1

	sub("([[:digit:]]{4})", "\\15", "12346789")