## -----------------------------------------------------------------------------
b <- 10:15
b


## -----------------------------------------------------------------------------
b[1]


## -----------------------------------------------------------------------------
b[2]


## -----------------------------------------------------------------------------
b[2:3]
# this is the same as
b[c(2,3)]
# or 
i <- 2:3
b[i]


## -----------------------------------------------------------------------------
b[c(1,3:6)]
# or the much simpler:
b[-2]


## -----------------------------------------------------------------------------
b[1] <- 11
b
b[3:6] <- -99
b


## -----------------------------------------------------------------------------
b[1:3] <- 2
b
b[3:6] <- c(10,20)
b


## -----------------------------------------------------------------------------
m <- matrix(1:9, nrow=3, ncol=3, byrow=TRUE)
colnames(m) <- c('a', 'b', 'c')
m


## -----------------------------------------------------------------------------
# one value
m[2,2]
# another one
m[1,3]


## -----------------------------------------------------------------------------
# 2 columns and rows
m[1:2,1:2]

# entire row
m[2, ]

# entire column
m[ ,2]


## -----------------------------------------------------------------------------
#single column
m[, 'b']
# two columns
m[, c('a', 'c')]


## -----------------------------------------------------------------------------
m[2,2]
# is equivalent to
m[5]


## -----------------------------------------------------------------------------
m[ ,2]


## -----------------------------------------------------------------------------
m[ , 2, drop=FALSE]


## -----------------------------------------------------------------------------
# one value
m[1,1] <- 5
m
# a row
m[3,] <- 10
m
# two columns, with recycling
m[,2:3] <- 3:1
m


## -----------------------------------------------------------------------------
diag(m)
diag(m) <- 0
m


## -----------------------------------------------------------------------------
m <- matrix(1:9, nrow=3, ncol=3, byrow=TRUE)
colnames(m) <- c('a', 'b', 'c')
e <- list(list(1:3), c('a', 'b', 'c', 'd'), m)


## -----------------------------------------------------------------------------
e[2]
e[[2]]


## -----------------------------------------------------------------------------
names(e) <- c('zzz', 'xyz', 'abc')


## -----------------------------------------------------------------------------
e$xyz
e[['xyz']]


## -----------------------------------------------------------------------------
d <- data.frame(m)
class(d)


## -----------------------------------------------------------------------------
d[,2]


## -----------------------------------------------------------------------------
d[2]


## -----------------------------------------------------------------------------
d[, 'b']


## -----------------------------------------------------------------------------
d$b
# or this
d[['b']]


## -----------------------------------------------------------------------------
d['b']


## -----------------------------------------------------------------------------
d[ , 'b', drop=FALSE]


## -----------------------------------------------------------------------------
x <- 10:20
i <- which(x > 15)
x
i
x[i]


## -----------------------------------------------------------------------------
x <- 10:20
b <- x > 15
x
b
x[b]


## -----------------------------------------------------------------------------
x <- 10:20
j <- c(7,9,11,13) 
j %in% x
which(j %in% x)


## -----------------------------------------------------------------------------
match(j, x)


## -----------------------------------------------------------------------------
match(x, j)