R(week 12)

set.seed(125)
myMat <- matrix(rpois(20, 3), nrow = 4)
myMat
dim(myMat)



apply(myMat, 2, max)
apply(myMat, 1, min)
apply(myMat, 2, range)
airquality

split(airquality$wind, airquality$Month) %>%
  
split(airquality[])

lapply(1:5, rnorm)
lapply(1:4, rnorm, mean = 10)
lapply(1:5, rnorm, n = 5)

#split(airquality$Temp, airquality$Month) %>%
#  lapply(mean, na.rm = )
list1 <- list(A = matrix(1:16, 4), B = matrix(1:16, 2), C=1:5)
list2 <- list(A = matrix(1:16, 4), B=matrix(1:16, 8), C=15:1)
list1
mapply(identical,list1, list2)
?mapply

#chengji tongji 
library(tidyverse)
getNum <- function(n){
  myName <- sample(letters, n, replace = TRUE) %>%
    paste0(collapse = "") %>%
    str_to_title()
  return (myName)
}
getNum(4)
stNames <- c()
for(i in 1:50){
  gName <- getNum(sample(2:8, 1))
  fName <- getNum(sample(2:3, 1))
  stNames[i] <- paste(gName, fName)
}
stNames

English <- sample(30:100, 50, replace = TRUE)
Management <- sample(70:89, 50, replace = TRUE)
Rdatascience <- sample(60:100, 50, replace = TRUE)

roster <- data.frame(stNames, English, Management, Rdatascience)
dim(roster)
view(roster)
ave_score <- roster[ ,-1] %>%
  apply(1, mean)
roster1 <- cbind(roster, ave_score)
view(roster1)