Summary Introduction to Programming Course Commands Guide

● cat(“ “) → display a sentence on the screen
Cat without quotation is used to display variables. Ex. a=3, cat(a), 3 is displayed


● typeof → show what kind of variable it is


OPERATIONS FOR NUMERIC VARIABLES


● + → addition
● - → subtraction
● * → multiplication
● %/% → floor division: without decimals (rounded)
● %%==0 → modulus: check if remainder of a division is 0
● %%# → modulus: divide numbers by # and extract the remainder of the division


READLINE


● readline(”TEXT”) → Ask for information from the user of the script. Always
character variable


To convert readline variables into other variables:
● variable = as.numeric(variable)
● variable = as.integer(variable)
● variable = as.character(variable)
● variable = as.logic = (variable)


COMMANDS FOR CHARACTER VARIABLES


● nchar(text_variable) → number of characters in text_variable


● toupper(text_variable) → put in uppercase


● tolower(text_variable) → put in lowercase

, ● gsub(“st”,”street”, text) → change “st” for “street” in text


● trimws(text_variable) → delete unnecessary spaces


● gsub(“ “,””,name of variable) → to delete all spaces in a variable


● grepl(“word”, text_variable) → check if a word is in the variable
Transform word to lower case first


● substr(text_variable, number, number) → Show the characters in position of first
number until the second number


● paste0(variable 1, variable 2) → paste two variables together


CONDITIONAL STATEMENTS


If (condition a) {


if it is false, then…

}else if (condition b)
….


}else{
}
Final else is optional and always without condition


For conditions:
● a > b → greater than
● a < b → less than
● a == b → equal to
● a & b → a and b
● a|b → a or b


LOOPS