Compare matrices to find the differences

Question

I have 2 matrices, I want to compare them (row.name wise) to find the difference.

> head(N1)
              Total_Degree Transitivity Betweenness Closeness         


        

Answer 1

That is a part of the solution, in res you have a data.table to work with for the difference part:

require(data.table)
require(dplyr)

set.seed(2016)
dt1 <- data.table(V1 = c("a", "b", "c", "d"), V2 = rnorm(4))
dt2 <- data.table(V1 = c("c", "d", "e", "f"), V2 = rnorm(4))

# common <- merge(dt1, dt2, by = "V1")[, Unique := "Common"]
# unique1 <- dt1[V1 %nin% dt2[, V1], ][, Unique := "N1"]
# unique2 <- dt2[V1 %nin% dt1[, V1], ][, Unique := "N2"]
# res <- rbind(common, unique1, unique2, fill = TRUE)

Small update after @Cath answer, just for clarity.

allMerged <- merge(dt1, dt2, by = "V1", all = TRUE) %>%
  .[, RowSum := rowSums(.SD, na.rm = TRUE), .SDcols = grep("V2", names(.))] %>%
  .[, Unique := ((is.na(V2.x) + 2*is.na(V2.y)))]

print(allMerged)

Answer 2

A way to go in base R, with rowSums and merge:

If N1 and N2 are data.frames:

# compute the row sums and merge N1 and N2
N1$rs <- rowSums(N1, na.rm=TRUE)
N2$rs <- rowSums(N2, na.rm=TRUE)
comp <- merge(N1[, "rs", drop=FALSE], N2[, "rs", drop=FALSE], by="row.names", all=TRUE)

# then compare the row sums and the variable "locations"
comp$Unique <- with(comp, c("N1", "N2", "common")[(!is.na(rs.x)) + 2*(!is.na(rs.y))])
comp$Comparison <- with(comp, rs.x-rs.y)

# keep only the variable you need:
comp <- comp[, c(1, 5, 4)]

If N1 and N2 are matrices:

# compute the row sums and merge N1 and N2
rs1 <- rowSums(N1, na.rm=TRUE)
rs2 <- rowSums(N2, na.rm=TRUE)
comp <- merge(N1, N2, by="row.names", all=TRUE)

# then compare the row sums and the variable "locations"
comp$Unique <- with(comp, c("N1", "N2", "common")[as.numeric(!is.na(Total_Degree.x)) + 2*as.numeric(!is.na(Total_Degree.y))])
comp$Comparison <- with(merge(as.data.frame(rs1), as.data.frame(rs2), all=TRUE, by="row.names"), rs1-rs2)

# keep only the variable you need:
comp <- comp[, c("Row.names", "Comparison", "Unique")]

output of both methods:

comp
#      Row.names    Comparison Unique
#1 2410016O06RIK  0.0000844042 common
#2          ADI1            NA     N2
#3          AGO1 -1.8332483856 common
#4          AIRN            NA     N2
#5         APEX1  3.0000856324 common
#6           ATR  0.8334181369 common
#7         CASP3            NA     N1
#8         CCND2            NA     N1