How to create a presence-absence matrix?

Question

I have an Excel table (.csv), like this (with duplicate species):

Species     Site 
Panthera    A 
Panthera    B 
Panthera    C 
Neofelis    B 
Neofelis    D

and I would like to use R to create a presence-absence matrix, like this:

Site    Panthera    Neofelis
A          1           0
B          1           1
C          1           0
D          0           1

How I could do it, please? Thanks!

@DavidArenburg, I cannot find information about the function of the arguments [2:1]. Could you explain it, please? — M.S., Mar 14 '17 at 18:38
I just reordered the columns in order to match your desired output. You could as well just do `table(df)` but then the result will be transposed. — David Arenburg, Mar 14 '17 at 18:40

score 4 · Accepted Answer · answered Mar 14 '17 at 16:04

4

We can use dcast

library(reshape2)
dcast(df1, Site~Species, length)

answered Mar 14 '17 at 16:04

akrun

1 Answers1