Homework_10

library(ggplot2)

Question #1

vector <- rbinom(n=20, size = 0:10, prob = 0.5)

counter <- 0

vec_zeros <- function(vector) {
 for (i in seq_along(vector)) {
   if (vector[i] == 0) {
     counter <- counter + 1
   }
   return(counter)
 }
}

Question #2

sub_zeros <- function(vector) {
  return(sum(vector == 0))
}

Question #3

vec_matrix <- function(rows, columns) {
  m <- matrix(NA, nrow = rows, ncol = columns)
  for (i in 1:nrow(m)) {
    for (j in 1:ncol(m)) {
      m[i,j] <- i*j
    }
  }
  return(m)
}

Question #4

#a 

groups <- c("a", "b", "c")

vars <- c(rnorm(n = 20, mean = 10),
          rnorm(n = 20, mean = 20),
          rnorm(n = 20, mean = 30))

df <- data.frame(groups,vars)

#b

shuffle <- function(n = 10, means = c(10, 20, 30)) {
  var1 <- rnorm(n = n, mean = means[1])
  var2 <- rnorm(n = n, mean = means[2])
  var3 <- rnorm(n = n, mean = means[3])
  avgs <- c(mean(var1), mean(var2), mean(var3))
  return(avgs)
}

#c

df2 <- data.frame(rep = NA, a = NA, b = NA, c = NA)
 for (i in 1:100) {
   rep_data <- shuffle(df)
   df2[i, 1:4] <- c(i, rep_data)
 }
head(df2)

##   rep         a        b        c
## 1   1 10.050854 20.08542 29.78820
## 2   2 10.041449 21.13586 30.50175
## 3   3 10.196622 20.38981 30.79304
## 4   4 10.066933 20.74551 30.03030
## 5   5  9.969958 19.72048 30.37813
## 6   6  9.987650 19.17907 30.31938

#d

qplot(data = df2, x = a, geom = "histogram")

## Warning: `qplot()` was deprecated in ggplot2 3.4.0.
## This warning is displayed once every 8 hours.
## Call `lifecycle::last_lifecycle_warnings()` to see where this warning was
## generated.

## `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.

qplot(data = df2, x = b, geom = "histogram")

## `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.

qplot(data = df2, x = c, geom = "histogram")

## `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.

#The reshuffled means are not always exactly the original specified mean. However, the reshuffled means very close to the original mean and are normally distributed.