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##  Code of Slides:  Basic Concepts of the R Language
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####### Section:  Basic Interaction

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1+3/5*6^2

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rnorm(5,mean=30,sd=10) 

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# function composition example
mean(sample(1:1000,30)) 

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plot(sample(1:10,5),sample(1:10,5),
     main="Drawing 5 random points",xlab="X",ylab="Y")


####### Section:  Variables and Objects

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vat <- 0.20

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priceVAT <- 240 * (1 + vat)

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k <- 10
g <- k/2
x <- g*2

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x <- 23^3
x

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x <- true

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x <- 23
x
x <- 4
x


####### Section:  Vectors

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prices <- c(32.4,35.4,30.2,35,31.99)
prices

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prices <- c(worten=32.4,fnac=35.4,mediaMkt=30.2,radioPop=35,pixmania=31.99)
prices

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barplot(prices)


####### Section:  Indexing

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prices <- c(worten=32.4,fnac=35.4,
            mediaMkt=30.2,radioPop=35,pixmania=31.99) 
prices[3]

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prices <- c(worten=32.4,fnac=35.4,
            mediaMkt=30.2,radioPop=35,pixmania=31.99) 
prices["worten"]

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prices[worten]

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prices <- c(worten=32.4,fnac=35.4,
            mediaMkt=30.2,radioPop=35,pixmania=31.99) 
prices[c(2,4)]

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prices[c("worten","pixmania")]

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prices[prices > 35]

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prices[prices > mean(prices)]


####### Section:  Vectorization

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vat <- 0.23
(1+vat)*prices

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sqrt(prices)

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prices2 <- c(worten=32.5,fnac=34.6,mediaMkt=32,
             radioPop=34.4,pixmania=32.1)
prices2

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(prices+prices2)/2

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prices > 35


####### Section:  Matrices

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prc <- matrix(c(32.40,35.40,30.20, 35.00, 31.99, 
                32.50, 34.60, 32.00, 34.40, 32.01),
              nrow=2,ncol=5,byrow=TRUE)
prc

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prc <- matrix(c(32.40,35.40,30.20, 35.00, 31.99, 
                32.50, 34.60, 32.00, 34.40, 32.01),
              nrow=2,ncol=5,byrow=TRUE)
prc

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prc
prc[2,4]

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prc[1,]
prc[,2]

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colnames(prc) <- c("worten","fnac","mediaMkt","radioPop","pixmania")
rownames(prc) <- c("porto","lisboa")
prc

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prc["lisboa",]
prc["porto","pixmania"]


####### Section:  Lists

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lst <- list(id=12323,name="John Smith",
            grades=c(13.2,12.4,5.6))
lst

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lst$grades

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lst[c('name','grades')]

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lst[[2]]

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lst[2]


####### Section:  Data Frames

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stud <- data.frame(nrs=c("43534543","32456534"),
                   names=c("Ana","John"),
                   grades=c(13.4,7.2))
stud

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stud <- edit(stud)

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stud

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stud[2,3]
stud[1,"names"]

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stud[1:2,]

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stud[,c("names","grades")]

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stud[stud$grades > 13,"names"]

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stud[stud$grades <= 9.5, c("names","grades")]

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subset(stud,grades > 13,names)
subset(stud,grades <= 9.5,c(nrs,names))