# Title:  Degbugging in R
# Student name 1:
# Student name 2:
# Instructions: Please add comments for each bug you have found and fix it, such as: # bug 1, forget a comma. 
# Comments (e.g, known bugs, questions you would like Dr. Cao to go through in the class, etc):


c1 <- "Hello World"
c2 <- c(123,c1)
c12 <- paste(c1 + c2,sep="")

v3 <= c2[0] + 10 
print(v3). 
print(substr(c12,2,40)

x <- c(0/0, 1/0, 100, 200L)
x(!as.na(x))       # get none NA values from x 

x <- list(c1, v3, x2)
print(x(2) + 10) 

v1 <- seq(1,10,2)
v2 <- seq(2,20,2)
m<- matrix(cbind(v1,v2))

x <- data.frame(foo = 1:4, bar = c(T, T, F, F)) 
print(x$"foo"[1])       # get first value in foo column 

m1 <- matrix(1:6,2,3)
m1[2,1]                  # want  to print 4, but it is not 4 

x <- c(1,3,5,7)
y <- c(x+1)             # value of y should be 2,4,6,8 

m2 <- matrix(2:7,3,2)  
m12Mutiply <- m1 * m2     # I want to do the true matrix multiplication, but don't know why it's not working 

if(x[1]%2 == 0) 
{
   print("x[1] is even number")
}

data <- matrix(1:1000,100,10) 
for(i in data[[7]])       # I want to check data in 7 column, skip numbers less than 500, and exit the loop if a number is larger than 800 
{ 
   if( i < 500 ) 
   {
     next 
   } 
}else( i > 800)} print(i) break 


# I want to check data in 7 column, skip numbers less than 500, and exit the loop if a number is larger than 800
for(i in data[[7]]) { print[i,7]  if(data[[i,7]] >= 500 & data[[i,7]] <= 800) }



cost <- c(50, 75, 90, 100, 150)
food <- c("pizza", "burgers", "salads", "cheese", "pasta", "pasta")
names(cost) <- food

print(cost[0:3])   #I want to print the cost for first three food
print(cost[2,3])   # I want to print cost for "Burgers" and "salads" 

print(cost.length) # I want to have the length of cost object 
n1 <- seq(1:100,2) # I want to Create a vector containing all the positive odd numbers smaller than 100.

print(which.min(cost)) # print the minimum cost, learn which.min by yourself 

temp <- c(35, 88, 42, 84, 81, 30)
city <- c("Beijing", "Lagos", "Paris", "Rio de Janeiro", "San Juan", "Toronto")
city_temps <- dataFrame(name = city, temperature = temp) 

print(mean(temp2[!is.na(temp)]))   # print the average temp for not NA 

temp <- (temp2 - 32)*5/9       # convert temperature into Celsius and overwrite the original values

x <- seq(1:100)       # create x with the numbers 1 through 100
sum(1/x^2)            # Compute the sum 1 + 1/2^2 + 1/3^2 + ... + 1/100^2

x <- rnorm(1000, 0, 100)  # generate 1000 random numbers 
low <- x<=0 
which(low)              # get all negative number
      
sum(x<ave(x))           # check how many of them are below average of x 

# whether or not each element of a first vector is in second vector we can use the function %in%
x <- c(2, 3, 5)
y <- c(1, 2, 3, 4)
x%in%y 

rank(-x)      # I want to rank x from lowest to highest, but it seems the output is not in the right order 

if(any(x>0))       
if(all(x>0)) 
  {
    print("All Positives")
  } else{
     print("Not All Positives")
  }

sum_n <- function(n){  # create a function to calculate sum of int from 1 to n
    x <- 1:n
    print(sum(x))           
}
sum_n(10) 

log_plot <- function(x, y){  # this function will not return anything, it will make plot
    plot(log10(x), log10(y))
}
log_plot(-1,100) 

# what happens for the following code:
x <- 3
my_func <- function(y){
    x <- 5
    y
    print(x)
}
my_func(x)        
x           # is x's value still 3? 

compute_s_n <- function(n){
  x <- 1:n
  sum(x^2)
}
compute_s_n(-100)      # I want to calculate sum of 1^2 + 2^2 +... + 100^2 

# Create a vector for storing results
s_n <- vector("numeric", 25)

# Assign values to `n` and `s_n`
for(i in 1:26){
  s_n[i] <- compute_s_n(i)
}
#another idea
for(i in 1:length(s_n)){
  s_n[i] <- compute_s_n(i)
}
#another idea 
for(i in 1:seq_along(s_n)){
  s_n[i] <- compute_s_n(i)
}

x<-0
system.time( for(i in 1:1e7) x <- x+i ) # "elapsed" gives us the total time needed to compute the command