How can I merge the columns of two data frames, containing a distinct set of columns but some rows with the same names? The fields for rows that don't occur in both data frames should be filled with zeros:
> d
a b c d e f g h i j
1 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10
2 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
> e
k l m n o p q r s t
1 11 12 13 14 15 16 17 18 19 20
3 21 22 23 24 25 26 27 28 29 30
> de
a b c d e f g h i j k l m n o p q r s t
1 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10 11 12 13 14 15 16 17 18 19 20
2 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0 0 0 0 0 0 0 0 0
3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 21 22 23 24 25 26 27 28 29 30
See ?merge:
the name "row.names" or the number 0 specifies the row names.
Example:
R> de <- merge(d, e, by=0, all=TRUE) # merge by row names (by=0 or by="row.names")
R> de[is.na(de)] <- 0 # replace NA values
R> de
Row.names a b c d e f g h i j k l m n o p q r s
1 1 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10 11 12 13 14 15 16 17 18 19
2 2 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0 0 0 0 0 0 0 0
3 3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 21 22 23 24 25 26 27 28 29
t
1 20
2 0
3 30
Source: Stackoverflow.com