Search notes:
R function: order
#
# Compare with -> rank
#
v <- c ( 41, 18, 37, 26)
order(v)
# [1] 2 4 3 1
# Definition of order:
# v[order(v)] is in increasing order:
v[order(v)]
# [1] 18 26 37 41
df <- data.frame(foo=c( 2, 3, 1),
bar=c( 22, 11, 22),
baz=c(111,333,222))
order(df$bar)
# [1] 2 1 3
df[order(df$bar) , ] # NOTE! the empty parameter «, ]»
# foo bar baz
# 2 3 11 333
# 1 2 22 111
# 3 1 22 222
order(df$bar, df$foo)
# [1] 2 3 1
df[order(df$bar, df$foo), ]
# foo bar baz
# 2 3 11 333
# 3 1 22 222
# 1 2 22 111
df[order(df$bar, df$baz), ]
# foo bar baz
# 2 3 11 333
# 1 2 22 111
# 3 1 22 222
df[order(df$bar, df$baz) ]
# bar foo baz
# 1 22 2 111
# 2 11 3 333
# 3 22 1 222