Hackerrank : 10 Days of Statistics in R [https://www.hackerrank.com/domains/tutorials/10-days-of-statistics]

day0a.r

# Day 0: Mean, Median, and Mode

# Selecting standard input
con <- file('stdin', open='r')

# We don't need the first input 
data_line <- readLines(con)[[2]]

# splitting the data into individual string
split_data <- strsplit(data_line, " ")

# String to integer conversion
data <- as.numeric(unlist(split_data))

# get mode function
getmode <- function(v) {
   v <- sort(v)
   uniqv <- unique(v)
   uniqv[which.max(tabulate(match(v, uniqv)))]
}


mean_value <- mean(data)
median_value <- median(data)
mode_value <- getmode(data)

cat(mean_value, sep="\n")
cat(median_value, sep="\n")
cat(mode_value, sep="\n")

day0b.r

# Day 0: Weighted Mean

con <- file('stdin', open='r')

inputs <- readLines(con)

# We don't need the first input 
data <- inputs[[2]]
weights <- inputs[[3]]

# Converts string to vector
stringToVector <- function(string){
    return (as.numeric(unlist(strsplit(string, " "))))
}

result <- sum(stringToVector(data) * stringToVector(weights)) / sum(stringToVector(weights)) 

# Formatting result 
cat(format(round(result, 1), nsmall=1))

day1a.r

# Day 1: Quartiles

# Enter your code here. Read input from STDIN. Print output to STDOUT

con <- file('stdin', open='r')

stringToVector <- function(string){
    return (as.numeric(unlist(strsplit(string, " "))))
}

data_line <- readLines(con)[[2]]

v <- stringToVector(data_line)

quart <- function(x) {
  x <- sort(x)
  n <- length(x)
  m <- (n+1)/2
  if (floor(m) != m) {
    l <- m-1/2; u <- m+1/2
  } else {
    l <- m-1; u <- m+1
  }
  o <- c(Q1=median(x[1:l]), median(x) ,Q3=median(x[u:n]))
  return (o)
}

x <- quart(v)

cat(x, sep="\n")

day1b.r

# Day 1: Interquartile Range

con <- file('stdin', open='r')

stringToVector <- function(string){
    return (as.numeric(unlist(strsplit(string, " "))))
}

inputs <- readLines(con)

data <- stringToVector(inputs[[2]])
repeatations <- stringToVector(inputs[[3]])

total_data <- c()

for (i in 1:length(data)){
    total_data <- c(total_data, rep.int(data[i], repeatations[i]))
}

total_data <- sort(total_data)

quart <- function(x) {
  x <- sort(x)
  n <- length(x)
  m <- (n+1)/2
  if (floor(m) != m) {
    l <- m-1/2; u <- m+1/2
  } else {
    l <- m-1; u <- m+1
  }
  return (median(x[u:n]) - median(x[1:l]))
}

cat(format(round(quart(total_data), 1), nsmall=1))

day1c.r

# Day 1: Standard Deviation

con <- file('stdin', open='r')

stringToVector <- function(string){
    return (as.numeric(unlist(strsplit(string, " "))))
}

std <- function(v){
    return (sd(v) * sqrt((length(v)-1)/length(v)))
}

inputs <- readLines(con)

data <- stringToVector(inputs[[2]])

cat(format(round(std(data), 1), nsmall=1))

day4a.r

# Enter your code here. Read input from STDIN. Print output to STDOUT

boy <- 1.09
girl <- 1
N <- 6
boy_atleast <- 3

p <- boy / (boy + girl)

combination <- function(n, x){
    return (factorial(n)/(factorial(x) * factorial(n-x)))
}

binomialDist <- function(X, N, P){
    return (combination(N, X) * P^X * (1-P)^(N-X))
}

leastBinomialDist <- function(R, N, P){
    result <- 0
    for (i in R:N){
        result <- result + binomialDist(i, N, P)
    }
    return (result)
}

res <- leastBinomialDist(boy_atleast, N, p)


cat(format(round(res, 3), nsmall=1))