sum specific values in a specific column in R using sum()

Question

I have a table of values 1, 2, 3, 4 randomly distributed across 35 rows and 15 columns. How can use the sum() function to just add the "4"s across the entire table, and also on a separate operation add all "4"s from a specific column.

Thanks,

This is the matrix:

m1imported <-matrix(sample(x = 1:4, size = 35*15, replace = TRUE), nrow = 35, ncol = 15)

us<c("CALIFORNIA","FLORIDA","ARIZONA","MICHIGAN","WASHINGTON","GEORGIA","TEXAS","OHIO","ALABAMA","COLORADO","NEW JERSEY","VIRGINIA","MONTANA","OREGON","NEW YORK")

colnames(m1imported) = us

num<-c(1:35)
rownames (m1imported) = num

question from:https://stackoverflow.com/questions/65913637/sum-specific-values-in-a-specific-column-in-r-using-sum

Answer 1

To count 4's across entire matrix :

sum(m1imported == 4)

To count 4's across each column.

colSums(m1imported == 4)

To sum 4's across entire matrix :

sum(m1imported==4)*4

To sum 4's across each column.

colSums(m1imported==4)*4

vector of females:

females <- c(m1imported[1:20,])

vector of males:

males <- c(m1imported[-1:-(nrow(m1imported)-15),])