CODEWITHSUNDEEP
rmatrix
h3ab74
h3ab74

Reputation: 328

Order table based on another table

I have seen many similar threads however, the examples I've seen tend to have a more linear trend to them and as such, do not apply to my problem.

I have a table that looks as such:

x1 x2
a  up
k  up
h  up
d  up
p  up
.  .
.  .

And another table with the EXACT same entries over x1, where NROW(table1) == NROW(table2), as such:

x1 x2
k  up
a  down
d  down
.  .
.  .

I want to reorder table1 based off x1 in table2, where the x1 and x2 variables will remain consistent in the output; a for example to still be up.

where the output would look like this:

x1 x2
k  up
a  up
d  up
.  .
.  .

Upvotes: 0

Views: 985

Answers (2)

Zahiro Mor
Zahiro Mor

Reputation: 1718

if you want to keep the table2$x1 order :

merge(table1,table2,by="x1")


  x1 x2.x x2.y
1  a   up   up
2  d   up down
3  k   up   up

and you can choose which column to delete

Upvotes: 1

csgroen
csgroen

Reputation: 2551

You can use match() to find the positions of x1 from the second table in the first table and re-order. Here's the result in your example. Let's reorder tab1 by tab2:

tab1 <- data.frame(x1 = c("a", "k", "h", "d", "p"),
           x2 = c("up", "up", "up", "up", "up"))

tab2 <- data.frame(x1 = c("k", "a", "d"),
                   x2 = c("up", "up", "down"))

idx <- match(tab2$x1, tab1$x1)
tab1[idx,]

This results in:

  x1    x2   
1 k     up   
2 a     up   
3 d     up

Upvotes: 1

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