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rdatedplyrreorderlist

sorting list of dataframes by date

I have a list of dataframes in a structure similar to this:

`ID1_01/05/10` <- data.frame(c(1,1))
`ID1_21/02/10` <- data.frame(c(2,1))
`ID2_01/05/10` <- data.frame(c(3,1))
`ID2_21/02/10` <- data.frame(c(4,1))
lst <- list(mget ( ls ( pattern = 'ID\\d+')))

I'd like to order them in the list first by identity and then by date. I.e.:

`ID1_21/02/10`
`ID1_01/05/10`
`ID2_21/02/10`
`ID2_01/05/10`

Is there a way of doing this easily?

Solution

  • We extract the names, get the numeric part ('v1') and the Date part, and order based on it

    nm1 <-  sapply(lst, names)[,1]
v1 <- as.numeric(sub(".*(\\d+)_.*", "\\1", nm1))
d1 <- as.Date(sub(".*_", "", nm1), "%d/%m/%y")
nm1[order(v1, d1)]
#[1] "ID1_21/02/10" "ID1_01/05/10" "ID2_21/02/10" "ID2_01/05/10"

lapply(lst, function(x) x[order(v1, d1)])
#[[1]]
#[[1]]$`ID1_21/02/10`
# c.2..1.
#1       2
#2       1

#[[1]]$`ID1_01/05/10`
#  c.1..1.
#1       1
#2       1

#[[1]]$`ID2_21/02/10`
#  c.4..1.
#1       4
#2       1

#[[1]]$`ID2_01/05/10`
#  c.3..1.
#1       3
#2       1

    Update

    In the OP's example, the mget was wrapped with list and it would create a list of lists. Instead it would be

    lst <- mget ( ls ( pattern = 'ID\\d+'))

    and if that is the case, then

    nm1 <- names(lst)
lst[order(v1, d1)]