Solutions des TPs
635
3.9- date1
date1+7
L’op´ eration ci-dessus a ajout´ e 7 secondes ` a date1.
3.10- date1+7 * 24 * 60 * 60
3.11- dates <- date1 + 7 * 24 * 60 * 60 * (0:(nrow(grippe)-1))
3.12- grippe$Date <- substring(dates,1,10)
3.13- masque1 <- (as.POSIXlt(dates) >= as.POSIXlt("1992-09-15"))
masque2 <- (as.POSIXlt(dates) <= as.POSIXlt("1993-11-03"))
portion <- grippe[masque1 & masque2,]
3.14- casgrippe <- colSums(portion[,-1],na.rm=TRUE)
casgrippe
E- Combinaison de tables ou de listes, autres manipulations
3.1- a <- matrix(1:6,3,2)
rownames(a) <- c(1,2,6)
b <- matrix(1:8,4,2)
rownames(b) <- c(3,4,5,7)
3.2- ab <- rbind(a,b)
ab <- ab[order(rownames(ab)),]
ab
3.3- list1 <- list()
list1[[1]] <- matrix(runif(25),nr=5)
list1[[2]] <- matrix(runif(30),nr=5)
list1[[3]] <- matrix(runif(15),nr=5)
matrix(unlist(list1),nrow=5)
# ou bien:
do.call(cbind,list1)
3.4- list2 <- list()
list2[[1]] <- matrix(runif(25),nc=5)
list2[[2]] <- matrix(runif(35),nc=5)
list2[[3]] <- matrix(runif(15),nc=5)
tmp <- lapply(list2,FUN=t)
t(matrix(unlist(tmp),nrow=5))
# ou bien:
do.call(rbind,list2)