strboul

days <- seq_along(1:365)
points <- list()

for (i in days) {
  points[[i]] <- exp(-i/500)
}

x <- unlist(points)
df <- cbind.data.frame(x, days)

strboul

# How much interest etc. would you pay for a mortgage?

compound <- function(rate, money, n) {
  prin <- money * (1+rate/100)^(0:(n-1))
  int  <- prin * (rate/100)
  totalInt <- sum(int)
  totalMoney <- money + totalInt
  rentpermonth <- totalMoney / (n * 12)
  textTable <- c(
                 cat(rep("=", 30), "\n ", sep=""),

strboul

############################################################
####              Anonymous functions in R              ####
############################################################

capitals <- c("Amsterdam", "Paris", "Warszawa", "Istanbul")
lapply(capitals, function(name) nchar(name))

# function with no name assigned to it, and does not appear in global env.:
{function(x) x^2}(5)
(function(x) x^2)(4) # without curly brackets

strboul

library(microbenchmark)
x <- sample(100000)
microbenchmark(x[order(x, method = "auto")],
               x[order(x, method = "shell")],
               x[order(x, method = "radix")])
# Unit: milliseconds
# expr       min        lq      mean    median        uq       max
# x[order(x, method = "auto")]  1.790454  1.863924  2.128368  1.930263  2.362573  3.328237
# x[order(x, method = "shell")] 17.530465 17.991802 18.914891 18.641179 19.763667 21.762103
# x[order(x, method = "radix")]  1.791103  1.847488  2.439882  1.975531  2.265257 33.209701

strboul

#' Convert strings to R objects
#'
#' @param x a string
#' @details It is particularly designed for the YAML strings that can be
#'   converted into R code. Strings to be evaluated should start with *`'r'`*
#'   letter and be surrounded with backticks. If this is not the case, it will
#'   return string as is. It is advised to keep all string in double quotes,
#'   otherwise unquoted strings will be converted by the yaml reader.
#' @noRd

strboul

#' Record the past input values 'only for a session'. Persistent store approach is different. 
#' This snippet has example for selecting rows in datatable from the DT package. Reference: 
#' https://stackoverflow.com/a/41199134

library(shiny)
library(DT)

ui <- fluidPage(
  dataTableOutput("dt")
)

strboul

# sink() sends output to stdout to get it written in a file.

# reports how many sink diversions are in use:
sink.number()

sink(file = "sink.log")
cat("hello")
runif(10)
cat(runif(10), sep = "\n")
sink(file = NULL) # be sure you closed the sink!

strboul

#!/bin/bash

set -e

DIR="/tmp/test-merge"

if [ -d "$DIR" ]; then 
	rm -rf "$DIR"
fi

strboul

#!/bin/bash -e

if ! [ -x "$(command -v shellcheck)" ]; then
  echo 'Program ShellCheck not found. Aborting.' >&2
  exit 1
fi

# finds either .sh or .bin files
if find . -type f \( -iname \*.sh -o -iname \*.bin \) -print0 | xargs -n1 -0 shellcheck -s bash; then
    echo -e "ShellCheck lint test passed!"

strboul

#!/bin/bash
# M Y 2018-08-21. An example script on Docker volumes showing
# how to run a sandboxed 'R' code inside the container.
# Tip: Using `ls` (or else) with the volumes is helpful especially
# when need to understand why some particular files cannot be found.

set -x

V="rvol"
mkdir $V