## ----------------------------------------------------------------------------- a <- 7 ## ----------------------------------------------------------------------------- a = 7 ## ----------------------------------------------------------------------------- show(a) print(a) ## ----------------------------------------------------------------------------- a ## ----------------------------------------------------------------------------- class(a) ## ----------------------------------------------------------------------------- a <- as.integer(7) class(a) a <- 7L class(a) ## ----------------------------------------------------------------------------- b <- c(1.25, 2.9, 3.0) b ## ----------------------------------------------------------------------------- d <- 5:9 d ## ----------------------------------------------------------------------------- 6:2 ## ----------------------------------------------------------------------------- seq(2,5,1) seq(from=6, to=12, by=3) ## ----------------------------------------------------------------------------- seq(from=12, to=0, by=-4) ## ----------------------------------------------------------------------------- s <- seq(from=0, to=12, by=4) s r <- rev(s) r ## ----------------------------------------------------------------------------- rep(9, times=5) rep(5:7, times=3) rep(5:7, each=3) ## ----------------------------------------------------------------------------- x <- "Yi" y <- "Wong" class(x) x ## ----error = TRUE------------------------------------------------------------- Yi ## ----------------------------------------------------------------------------- countries <- c("China", "China", "Japan", "South Korea", "Japan") class(countries) countries ## ----------------------------------------------------------------------------- length(countries) ## ----------------------------------------------------------------------------- nchar(countries) ## ----------------------------------------------------------------------------- z <- letters z up <- toupper(z) up ## ----------------------------------------------------------------------------- girl <- "Mary" boy <- "John" paste(girl, "talks to", boy) ## ----------------------------------------------------------------------------- paste(girl, "likes", boy, sep = " ~ ") ## ----------------------------------------------------------------------------- paste(countries, collapse=" -- ") ## ----------------------------------------------------------------------------- substr("Hello World", 1, 5) substr("Hello World", 7, 11) ## ----------------------------------------------------------------------------- gsub("l", "!!", "Hello World") gsub("Hello", "Bye bye", "Hello World") ## ----------------------------------------------------------------------------- d <- c("az20", "az21", "az22", "ba30", "ba31", "ab32") i <- grep("ba", d) i d[i] # or like this grep("ba", d, value=TRUE) ## ----------------------------------------------------------------------------- # Instead of the index, get logical values with grepl i <- grepl("ba", d) i # return the cases of d for which i is TRUE d[i] ## ----------------------------------------------------------------------------- grep("2", d) ## ----------------------------------------------------------------------------- grep("2$", d) ## ----------------------------------------------------------------------------- grep("^b", d) ## ----------------------------------------------------------------------------- z <- FALSE z class(z) z <- c(TRUE, TRUE, FALSE) z ## ----------------------------------------------------------------------------- x <- 2:5 x > 3 ## ----------------------------------------------------------------------------- x == 3 x <= 2 ## ----------------------------------------------------------------------------- y <- TRUE y + 1 ## ----------------------------------------------------------------------------- as.logical(0) as.logical(1) as.logical(2.5) ## ----------------------------------------------------------------------------- f1 <- as.factor(countries) f1 ## ----------------------------------------------------------------------------- f2 <- c(5:7, 5:7, 5:7) f2 f2 <- as.factor(f2) f2 ## ----------------------------------------------------------------------------- f2 as.integer(f2) ## ----------------------------------------------------------------------------- fc2 <- as.character(f2) fc2 as.integer(fc2) ## ----------------------------------------------------------------------------- m <- c(2, NA, 5, 2, NA, 2) m ## ----------------------------------------------------------------------------- d1 <- as.Date("2015-4-11") d2 <- as.Date("2015-3-11") class(d1) d1 - d2 ## ----------------------------------------------------------------------------- as.POSIXlt(d1) as.POSIXct(d1)