R replace multiple columns by merging another data

Question

I want to replace mupltiple columns by merging another data. For example: I have two data frames, I want to replace columns of dat2 by using dat1.

  set.seed(1234)
  dat1 = data.frame(userId = c(1:10), value = sample(100, 10))
  #    userId value
  # 1       1    84
  # 2       2    29
  # 3       3    27
  # 4       4    19
  # 5       5    23
  # 6       6    31
  # 7       7    99
  # 8       8    15
  # 9       9     4
  # 10     10    20

  dat2 = data.frame(var1 = 1:5, var2 = 10:6, var3 = sample(10, 5))
  #   var1 var2 var3
  # 1    1   10    7
  # 2    2    9    5
  # 3    3    8    3
  # 4    4    7   10
  # 5    5    6    2

Expected output:

  # > dat2
  #   var1 var2 var3
  # 1   84   20   99
  # 2   29    4   23
  # 3   27   15   27
  # 4   19   99   20
  # 5   23   31   29

BENY · Accepted Answer · 2018-07-16 02:14:29Z

3

Using lapply with match

as.data.frame(lapply(dat2,FUN = function(x) dat1$value[match(x,dat1$userId)]))
  var1 var2 var3
1   12   47    1
2   62   99   83
3   60   22   60
4   61    1   47
5   83   97   62

answered Jul 16, 2018 at 2:14

BENY

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Comments

Onyambu · Accepted Answer · 2018-07-16 02:19:43Z

0

You can use unstack and stack

unstack(transform(stack(dat2),n=dat1$value[match(values,dat1$userId)]),n~ind)
  var1 var2 var3
1   12   47    1
2   62   99   83
3   60   22   60
4   61    1   47
5   83   97   62

answered Jul 16, 2018 at 2:19

Onyambu

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Comments

akrun · Accepted Answer · 2018-07-16 02:48:12Z

0

Another base R option is

dat2[] <- with(dat1, setNames(value, userId)[as.matrix(dat2)])
dat2
#  var1 var2 var3
#1   12   47    1
#2   62   99   83
#3   60   22   60
#4   61    1   47
#5   83   97   62

answered Jul 16, 2018 at 2:48

akrun

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