dataframe - R: any function for Cartesian Product of two data frames? -


this question has answer here:

i need cartesian product of 2 data frames. example,

 = id weight type      10    20          10    30     b      25    10     c  b = date  report      2007    y      2008    n

then c after doing cartesian product of , b

 c =  id weight type  date  report       10    20        2007    y       10    20        2008    n       10    30     b    2007    y       10    30     b    2008    n       25    10     c    2007    y       25    10     c    2008    n

as ids same in a, cannot use way 

c <- merge(a$id,b$date) c <- merge(c,a,by="id") c <- merge(c,b,by="date")

this way generate more rows. me out of here? thanks

merge(a, b), provided there no columns linking two, should default, no?

from ?merge (emphasis mine):

if or both by.x , by.y of length 0 (a length 0 vector or null), result, r, cartesian product of x , y, i.e., dim(r) = c(nrow(x)*nrow(y), ncol(x) + ncol(y)).

admittedly, require 1 know in ?merge. context-based searching in r severely lacking; rseek doesn't provide this.


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