set.seed(42)1 R Basics
1.1 Generate Random Sample
set random seed to get same result for repeating
a random vector size of 20, follows to Normal Distribution
rnorm(20) [1] 1.37095845 -0.56469817 0.36312841 0.63286260 0.40426832 -0.10612452
[7] 1.51152200 -0.09465904 2.01842371 -0.06271410 1.30486965 2.28664539
[13] -1.38886070 -0.27878877 -0.13332134 0.63595040 -0.28425292 -2.65645542
[19] -2.44046693 1.32011335rnorm(20, mean = 10, sd = 2) [1] 9.386723 6.437383 9.656165 12.429349 13.790387 9.139062 9.485461
[8] 6.473674 10.920195 8.720010 10.910900 11.409675 12.070207 8.782147
[15] 11.009910 6.565983 8.431082 8.298185 5.171585 10.072245a random vector size of 10, follows to Uniform Distribution
runif(20) [1] 0.5816040025 0.1579052082 0.3590283059 0.6456318784 0.7758233626
[6] 0.5636468416 0.2337033986 0.0899805163 0.0856120649 0.3052183695
[11] 0.6674265147 0.0002388966 0.2085699569 0.9330341273 0.9256447486
[16] 0.7340943010 0.3330719834 0.5150633298 0.7439746463 0.6191592400runif(20, min = 0, max = 1) [1] 0.626245345 0.217157698 0.216567311 0.388945029 0.942455692 0.962608014
[7] 0.739855279 0.733245906 0.535761290 0.002272966 0.608937453 0.836801559
[13] 0.751522563 0.452731573 0.535789994 0.537376695 0.001380844 0.355665954
[19] 0.612133090 0.828942131runif(20, 0, 1) [1] 0.3567220 0.4106351 0.5734759 0.5896783 0.7196573 0.3949730 0.9192039
[8] 0.9625703 0.2335235 0.7244976 0.9036345 0.6034741 0.6315073 0.9373858
[15] 0.8504828 0.5798209 0.8214039 0.1137186 0.7645078 0.6236135prod(40:36)[1] 78960960prod(5:1)/prod(40:36)[1] 1.519738e-061/choose(40,5)[1] 1.519738e-06pvec <- seq(0,1,0.05)
pvec [1] 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70
[16] 0.75 0.80 0.85 0.90 0.95 1.00x <- rnorm(60000)
quantile(x, pvec) 0% 5% 10% 15% 20% 25%
-4.043276349 -1.656275635 -1.286941232 -1.045470141 -0.852443729 -0.684532015
30% 35% 40% 45% 50% 55%
-0.529470949 -0.387580521 -0.257069669 -0.124515346 0.002733696 0.126948433
60% 65% 70% 75% 80% 85%
0.251286891 0.381425011 0.524315026 0.675289348 0.843406262 1.033822369
90% 95% 100%
1.282235340 1.649455790 4.328091274 quantile(x) 0% 25% 50% 75% 100%
-4.043276349 -0.684532015 0.002733696 0.675289348 4.328091274 x.1 <- rnorm(20)
x.2 <- rnorm(20) + runif(20)
x.3 <- x.1 * 20 + x.2 * 4 - rnorm(20)
df <- data.frame(x1 = x.1, x2 = x.2, x3 = x.3)1.2 Matrix
A <- cor(df)
A x1 x2 x3
x1 1.0000000 0.1598481 0.9841209
x2 0.1598481 1.0000000 0.3275044
x3 0.9841209 0.3275044 1.0000000svd(A)$d
[1] 2.0934081396 0.9056768657 0.0009149947
$u
[,1] [,2] [,3]
[1,] -0.6617282 0.3025436 -0.6859906
[2,] -0.3022505 -0.9449705 -0.1252015
[3,] -0.6861198 0.1244917 0.7167576
$v
[,1] [,2] [,3]
[1,] -0.6617282 0.3025436 -0.6859906
[2,] -0.3022505 -0.9449705 -0.1252015
[3,] -0.6861198 0.1244917 0.7167576iA <- solve(A)
cA <- chol(A)
t(cA) %*% cA x1 x2 x3
x1 1.0000000 0.1598481 0.9841209
x2 0.1598481 1.0000000 0.3275044
x3 0.9841209 0.3275044 1.0000000solve(cA) %*% t(solve(cA)) x1 x2 x3
x1 514.61173 93.64606 -537.10967
x2 93.64606 18.16131 -98.10696
x3 -537.10967 -98.10696 561.71133solve(A) x1 x2 x3
x1 514.61173 93.64606 -537.10967
x2 93.64606 18.16131 -98.10696
x3 -537.10967 -98.10696 561.711331.3 string
astr <- as.character(12345)
bstr <- "NULL"
cstr <- "NOT LOWER, not upper"
c(astr, bstr, cstr)[1] "12345" "NULL" "NOT LOWER, not upper"nchar(astr)[1] 5c(toupper(cstr), tolower(cstr))[1] "NOT LOWER, NOT UPPER" "not lower, not upper"replace by vector
chartr("U", "L", bstr)[1] "NLLL"chartr("UL", "AI", bstr)[1] "NAII"substr
substr("HELLO", 2,3)[1] "EL"a = "12345678"
substr(a,2,2)[1] "2"substr(a,2,4)[1] "234"# substr(a,2)
# Error in substr(a, 2) : argument "stop" is missing, with no default
substring(a,2)[1] "2345678"substr(a,3,4) <- "Toyota"
a[1] "12To5678"substring(a,3) <- "Toyata"
a[1] "12Toyata"a = "12345"
b = "6789"
paste(a,b)[1] "12345 6789"paste(a,b,sep="")[1] "123456789"paste(a,b,sep="-")[1] "12345-6789"paste(a,b,sep = "honda")[1] "12345honda6789"a <- c('Taipei', "Tokyo", 'Singapore', 'Hong Kong', "Johor Baru", "Kuala Lumpr")
paste(a)[1] "Taipei" "Tokyo" "Singapore" "Hong Kong" "Johor Baru"
[6] "Kuala Lumpr"paste(a, "?", sep = "")[1] "Taipei?" "Tokyo?" "Singapore?" "Hong Kong?" "Johor Baru?"
[6] "Kuala Lumpr?"paste(a, "is where", sep = " ")[1] "Taipei is where" "Tokyo is where" "Singapore is where"
[4] "Hong Kong is where" "Johor Baru is where" "Kuala Lumpr is where"paste(a, "is where", sep = " ", collapse = ", and ")[1] "Taipei is where, and Tokyo is where, and Singapore is where, and Hong Kong is where, and Johor Baru is where, and Kuala Lumpr is where"strsplit(",,a,bb,", split = ",")[[1]]
[1] "" "" "a" "bb"strsplit(",,a,,", split = ",")[[1]]
[1] "" "" "a" "" strsplit(",,a,", split = ",")[[1]]
[1] "" "" "a"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"c("Hello")[1] "Hello"