r - Sort a data.frame by multiple columns whose names are contained in a single object? -

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i want sort data.frame multiple columns, ideally using base r without external packages (though if necessary, it). having read how sort dataframe column(s)?, know can accomplish order() function long either:

  1. know explicit names of each of columns.
  2. have separate object representing each individual column sort.

but if have 1 vector containing multiple column names, of length that's unknown in advance?

say vector called sortnames.

data[order(data[, sortnames]), ] won't work, because order() treats single sorting argument.

data[order(data[, sortnames[1]], data[, sortnames[2]], ...), ] work if , if specify exact correct number of sortname values, won't know in advance.

things i've looked @ not been totally happy with:

  1. eval(parse(text=paste("data[with(data, order(", paste(sortnames, collapse=","), ")), ]"))). maybe fine, i've seen plenty of hate using eval(), asking alternatives seemed worthwhile.
  2. i may able use deducer library sortdata(), said, i'd rather avoid using external packages.

if i'm being stubborn not using external packages, let me know. i'll on it. ideas appreciated in advance!

you can use do.call:

data<-data.frame(a=rnorm(10),b=rnorm(10))  data<-data.frame(a=rnorm(10),b=rnorm(10),c=rnorm(10)) sortnames <- c("a", "b") data[do.call("order", data[sortnames]), ]

this trick useful when want pass multiple arguments function , these arguments in convenient named list.


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