# File / Change dir


#nacteni souboru
heartdisease <- read.table("heartdisease.txt", header=TRUE,sep=",")

###   A retrospective sample of males in a heart-disease high-risk region
###   of the Western Cape, South Africa. There are roughly two controls per
###   case of CHD. Many of the CHD positive men have undergone blood
###   pressure reduction treatment and other programs to reduce their risk
###   factors after their CHD event. In some cases the measurements were
###   made after these treatments. These data are taken from a larger
###   dataset, described in  Rousseauw et al, 1983, South African Medical
###   Journal. 
###   
###   sbp		systolic blood pressure
###   tobacco		cumulative tobacco (kg)
###   ldl		low densiity lipoprotein cholesterol
###   adiposity
###   famhist		family history of heart disease (Present, Absent)
###   typea		type-A behavior
###   obesity
###   alcohol		current alcohol consumption
###   age		age at onset
###   chd		response, coronary heart disease


#promenne, zakladni popis
head(heartdisease)
summary(heartdisease)             


#aktivujeme ramec
attach(heartdisease)

#kategorizace promennych
sbp.kat <- cut(sbp,c(0,120,140,160,180,Inf),right=F,labels=c("Normotenze","Prehypertenze","Hypertenze I","Hypertenze II","Hyp. krize"))
obes.kat <- cut(obesity,c(0,20,25,30,Inf),right=F,labels=c("Podvaha","Normalni","Nadvaha","Obezita"))




#POPIS PROMENNYCH


#kvalitativni promenne

#tabulka
sbp.table <- table(sbp.kat)
sbp.table
prop.table(sbp.table)

#graf
barplot(sbp.table)
pie(sbp.table)


#kvantitativni promenne

hist(sbp)
qqnorm(sbp)



#VZTAHY MEZI PROMENNYMI

# 2 kvalitativni

#tabulka
sbpobes.table <- table(sbp.kat,obes.kat)
sbpobes.table
prop.table(sbpobes.table,2)

#graf
barplot(sbpobes.table,beside=T,legend.text=rownames(sbpobes.table))

par(mar=c(5, 4, 4, 10) + 0.1)
barplot(prop.table(sbpobes.table,2),xlab="Telesna hmotnost",ylab="Zastoupeni - krevni tlak",legend.text=rownames(sbpobes.table),args.legend = list(x = 7,y=0.9))

mosaicplot(sbpobes.table)


# 2 kvantitativni

plot(adiposity,obesity)
pairs(heartdisease)


# kvalitativni vs. kvantitativni

par(mfrow=c(1,2))
boxplot(sbp~obes.kat)
stripchart(sbp~obes.kat,vertical = TRUE,method = "jitter")