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Asked: 2026-05-26T07:19:48+00:00

I have a list of data.frames. A <- list(aa = data.frame(var1 = c(1:3), varb

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I have a list of data.frames. 

A <- list(aa = data.frame(var1 = c(1:3), varb = c(1:3), abu = c(1:3)), 
          bb = data.frame(abu = c(1:3), var1 = c(1:3), vara = c(1:3), varb = c(1:3)), 
          cc = data.frame(varb = c(1:3), g = c(1:3)))

output

> A
$aa
  var1 varb abu
1    1    1   1
2    2    2   2
3    3    3   3

$bb
  abu var1 vara varb
1   1    1    1    1
2   2    2    2    2
3   3    3    3    3

$cc
  varb g
1    1 1
2    2 2
3    3 3

>

How can I order variables in these data.frames so that the order of the variables is the same as the data.frame $aa has? If the data.frame does not have a correspondign variable, the variable should be created into this data.frame containing NA data. Any idea how to achieve this?

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1 Answer

  1. Editorial Team

    do you want something like this?

    > lapply(A, function(x) {
+   x[(setdiff(names(A$aa), names(x)))] <- NA
+   x[names(A$aa)]
+ })
$aa
  var1 varb abu
1    1    1   1
2    2    2   2
3    3    3   3

$bb
  var1 varb abu
1    1    1   1
2    2    2   2
3    3    3   3

$cc
  var1 varb abu
1   NA    1  NA
2   NA    2  NA
3   NA    3  NA

    How do you want to do with the variables that do not appear in A$aa, for example, A$bb$vara?

    Slightly updated for preserving other variables

    > lapply(A, function(x) {
+   x[setdiff(names(A$aa), names(x))] <- NA
+   x[c(names(A$aa), setdiff(names(x), names(A$aa)))]
+ })
$aa
  var1 varb abu
1    1    1   1
2    2    2   2
3    3    3   3

$bb
  var1 varb abu vara
1    1    1   1    1
2    2    2   2    2
3    3    3   3    3

$cc
  var1 varb abu g
1   NA    1  NA 1
2   NA    2  NA 2
3   NA    3  NA 3
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