Get a square matrix out of a non symetric data frame

Question

I\'m a total beginner in R. I have a series of data relating the surnames of married persons.

    Id_mar  Wife  Husband
1      1    Smith Johnson
2      2    Sm         


        

Answer 1

Based on the expected output, we can use table (as @David Arenburg mentioned in the comments) on factor converted 'Wife' and 'Husband' columns, specifying the levels as the sorted unique elements of both the columns ('Un1')

 Un1 <- sort(unique(unlist(df1[-1])))
 table(factor(df1$Wife, levels=Un1), factor(df1$Husband, levels=Un1))
 #          Carter Johnson Smith Wang White
 # Carter       0       0     0    0     0
 # Johnson      0       0     0    0     0
 # Smith        1       1     0    0     0
 # Wang         0       0     1    0     0
 # White        2       0     0    0     0

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Or we can use mtabulate from qdapTools.

 library(qdapTools)
 mtabulate(as.data.frame(t(df1[-1])))