#01
search()
ls()
ls(pos=2)
#02
help(abs)
?abs
#03
5 %% 2
7 %% 3
#04
increment=function(x) { x+1 }
#05
sent = "I'm feeling good."
sent = "I\'m feeling good."
sent = 'I\'m feeling good.'
#06
print(paste(c("ba",rep("na",2),"muffin."), collapse=""))
#07
age=readline("How old are you?")
#cat("How old are you?"); age=scan(what=numeric(), nmax=1)
#08
comp=function(n) {
ifelse(n>100, "More than 100.", ifelse(n>10, "10<n<=100.","n<=10."))
}
#09
grepl('mile','smiles')
grepl('smiles','mile')
#10
nchar('Hello')
#11
s='Call Me Maybe'
substring(s, 13, 13) # in R, index starts from 1
substring(s, nchar(s), nchar(s))
substring(s, 1, 4)
paste(substring(s, 1, nchar(s)-5),"Perhaps",sep="")
#12
regexpr("function",s) # s.find("function")
length(gregexpr("function",s)[[1]]) # s.count("function")
tolower(s)
#13
for (vowel in c('a','e','i','o','u'))
{ print(vowel) }
#14
num=6
while (num>0) {
print(num); num=num-1 }
#15
temperature = list(18, 20, 22.5, 24)
temperature[[4]]
temperature[4]
#16
length(list("math"))
nchar("math")
#17
grades=list(80, 90, 70)
grades <- c(grades, 3) #grades[[length(grades)+1]] = 3
grades[[length(grades)]]; grades[[length(grades)]]=NULL
grades=list(99, 77); append(grades, grades2)
grades[grades == 70] = NULL
#18
grades=list(80,70,60,90)
grades=as.list(sort(unlist(grades)))
#19
seq(1,10,2) # range(1,10,2)
lst=list(1,2,3)
seq(lst) # range(len(lst))
#20
lst=list(list(10,20),list(15),list(40,22))
total=0
for (sublist in lst) {
for (num in sublist) total=total+num }
#21
cat_string = readLines("cat.txt")
cat_string = paste(cat_string, collapse="\n")
#22
getwd()
#23
setwd("tempDir")