Include third variable in table [duplicate] - r

Question

This question already has answers here:
Contingency table based on third variable (numeric)
(2 answers)
Closed 4 years ago.
I have made an edit after realising my code was insufficient in order to explain to problem - appologies.
I have a data frame including four columns
purchaseId <- c("abc","xyz","def","ghi")
product <- c("a","b","c","a")
quantity <- c(1,2,2,1)
revenue <- c(500,1000,300,500)
t <- data.frame(purchaseId,product, quantity, revenue)
table(t$product,t$quantity)
Running this query
table(t$product,t$quantity)
returns a table indicating how many times each combination occurs
1 2
a 2 0
b 0 1
c 0 1
What I would like to do is plot both product and quantity as rows and columns (as shown above) but with the revenue as an actual value.
The result should look like this:
1 2
a 1000 0
b 0 1000
c 300 0
This would allow me to create a table that I could export as a csv.
Could anyone help me any further?
edit - the code suggested below throws the following error on the actual data set of 140K rows:
Error: dims [product 21525] do not match the length of object [147805]
Other ideas?
Of course the example code above is a simplified version of the actual data I'm using, but the idea is the same.
Thank you advance,
Kind regards.

Answer 1

table(t$product,t$quantity)*t$revenue

Answer 2

Using library(reshape2) or library(data.table)
dcast(t,product ~ quantity, value.var = "revenue", fun = sum)
it is fairly simple syntax:
Set the data frame you are recasting
Set the "formula" of the resulting data frame. LHS of ~ is the row-wise pivot, RHS is the column-wise.
value.var tells you what column we want to place in the cells, and using fun we want to aggregate with the sum function
As you mentioned in your comments familiarity with Excel Pivot tables, its worth noting that dcast is a fairly comprehensive replacement, with additional flexibility.