# A single loop is not enough. A collection of hello world control structures

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As the post on “hello world” functions has been quite appreciated by the R community, here follows the second round of functions for wannabe R programmer.

# If else statement: # See the code syntax below for if else statement x=10 if(x>1){ print(“x is greater than 1”) }else{ print(“x is less than 1”) } # See the code below for nested if else statement x=10 if(x>1 & x<7){ print(“x is between 1 and 7”)} else if(x>8 & x< 15){ print(“x is between 8 and 15”) } # For loops: # Below code shows for loop implementation x = c(1,2,3,4,5) for(i in 1:5){ print(x[i]) } # While loop : # Below code shows while loop in R x = 2.987 while(x <= 4.987) { x = x + 0.987 print(c(x,x-2,x-1)) } # Repeat Loop: # The repeat loop is an infinite loop and used in association with a break statement. # Below code shows repeat loop: a = 1 repeat{ print(a) a = a+1 if (a > 4) { break } } # Break statement: # A break statement is used in a loop to stop the iterations and flow the control outside of the loop. #Below code shows break statement: x = 1:10 for (i in x){ if (i == 6){ break } print(i) } # Next statement: # Next statement enables to skip the current iteration of a loop without terminating it. #Below code shows next statement x = 1: 4 for (i in x) { if (i == 2){ next } print(i) } # function words = c(“R”, “datascience”, “machinelearning”,”algorithms”,”AI”) words.names = function(x) { for(name in x){ print(name) } } words.names(words) # Calling the function # extract the elements above the main diagonal of a (square) matrix # example of a correlation matrix cor_matrix <- matrix(c(1, -0.25, 0.89, -0.25, 1, -0.54, 0.89, -0.54, 1), 3,3) rownames(cor_matrix) <- c(“A”,”B”,”C”) colnames(cor_matrix) <- c(“A”,”B”,”C”) cor_matrix rho <- list() name <- colnames(cor_matrix) var1 <- list() var2 <- list() for (i in 1:ncol(cor_matrix)){ for (j in 1:ncol(cor_matrix)){ if (i != j & i<j){ rho <- c(rho,cor_matrix[i,j]) var1 <- c(var1, name[i]) var2 <- c(var2, name[j]) } } } d <- data.frame(var1=as.character(var1), var2=as.character(var2), rho=as.numeric(rho)) d var1 var2 rho 1 A B -0.25 2 A C 0.89 3 B C -0.54

As programming is the best way to learn and think, have fun programming awesome functions! This post is also shared in R-bloggers and LinkedIn

A single loop is not enough. A collection of hello world control structures was first posted on July 13, 2020 at 5:47 am.

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