# 1.

X <- read.csv(file = "oil.csv", header = TRUE, sep = ";", dec = ",")
names(X)
str(X)
summary(X)
X$datum <- ISOdate(X$rok, X$mesic, X$den)

WTI <- X[X$typ == "WTI", ]
BRENT <- X[X$typ == "BRENT", ]
plot(WTI$datum, WTI$cena, type = "l", col = "red", xlab = "datum", ylab = "cena", ylim = c(0, 145))

lines(BRENT$datum, BRENT$cena, col = "blue")
legend("topleft", legend = c("WTI", "BRENT"), col = c("red", "blue"), lty = 1)

BRENT.r <- tapply(BRENT$cena, BRENT$rok, mean)
BRENT.r <- data.frame(cena = BRENT.r)
BRENT.r$rok <- as.numeric(rownames(BRENT.r))
BRENT.r$typ <- factor("BRENT")

WTI.r <- tapply(WTI$cena, WTI$rok, mean)
WTI.r <- data.frame(cena = WTI.r)
WTI.r$rok <- as.numeric(rownames(WTI.r))
WTI.r$typ <- factor("WTI")

plot(WTI.r$rok, WTI.r$cena, type = "l", col = "red", xlab = "rok", ylab = "prumerna rocni cena", ylim = c(0, 110))
lines(BRENT.r$rok, BRENT.r$cena, col = "blue")
legend("topleft", legend = c("WTI", "BRENT"), col = c("red", "blue"), lty = 1)
Y <- merge(WTI.r, BRENT.r, all = TRUE)
Z <- tapply(Y$cena, list(Y$rok, Y$typ), mean)
barplot(t(Z), beside = TRUE, col = c("red", "blue"), las = 2, xlab = "rok", ylab = "prumerna rocni cena")
legend("topleft", legend = c("WTI", "BRENT"), col = c("red", "blue"), lty = 1)

fn1 <- function (x) {
  return(x[2] - x[1])
  }
W <- apply(Z, 1, fn1)
barvy <- rep("green3", length(W))
barvy[W < 0] <- "yellow"
barplot(W, names.arg = rownames(W), las = 2, col = barvy, xlab = "rok", ylab = "rozdil prumerne rocni ceny BRENT - WTI ")

# 2. 

X <- read.csv(file = "titanic1.csv", header = TRUE, sep = ",", dec = ".")
X$pclass <- factor(X$pclass, levels = c(1, 2, 3), labels = c("class 1", "class 2", "class 3"))
X$survived <- factor(X$survived, levels = c(0, 1), labels = c("no", "yes"))
levels(X$embarked) <- c("Cherbourg", "Queenstown", "Southampton")
names(X)
str(X)
summary(X)

(T1 <- tapply(X$age, list(X$pclass, X$sex), length))
(T2 <- tapply(X$survived == "yes", list(X$pclass, X$sex), sum))
(T3 <- round(T2 / T1 * 100, digits = 1))
apply(T1, 2, sum)
apply(T1, 1, sum)
barplot(t(T1), col = c("red", "cyan"), xlab = "cestovni trida", ylab = "pocet cestujicich")
legend("top", legend = levels(X$sex), fill = c("red", "cyan"))
barplot(t(T2), col = c("red", "cyan"), xlab = "cestovni trida", ylab = "pocet prezivsich cestujicich")
legend("top", legend = levels(X$sex), fill = c("red", "cyan"))

(T4 <- round(tapply(X$age, list(X$pclass, X$sex), mean, na.rm = TRUE), digits = 1))
Y <- X[X$survived == "yes", ]
(T5 <- round(tapply(Y$age, list(Y$pclass, Y$sex), mean, na.rm = TRUE), digits = 1))

(T6 <- round(tapply(X$fare, list(X$pclass, X$sex), mean, na.rm = TRUE), digits = 1))
(T7 <- round(tapply(X$fare, list(X$pclass, X$sex), max, na.rm = TRUE), digits = 1))

(T8 <- table(X$survived, X$sex))

(sance.pro.zeny <- T8[2, 1] / T8[1, 1])
(sance.pro.muze <- T8[2, 2] / T8[1, 2])
(pomer.sanci <- sance.pro.zeny / sance.pro.muze)