R for loop wise : Rowwise sum on conditions : Performance issue

Question

I have a database, where I am running code to change value of a cell-based on the sum of previous cells and the sum of succeeding cells in the same row.

for (i in 1:row1) 
  
{      
  for(j in 3:col-1) 
  {       # for-loop over columns
    
      if (as.numeric(rowSums(e[i,2:j])) == 0 ) 
      {
        
        e1[i,j] <- 0
        
      }
      else if (as.numeric(rowSums(e[i,2:j])) > 0 &&  e[i,j] == 0 && as.numeric(rowSums(e[i,j:col])) > 0 ) 
      {
        e1[i,j] <- 1
      }
      
      else if (as.numeric(rowSums(e[i,2:j])) > 0 &&  e[i,j] == 1 && as.numeric(rowSums(e[i,j:col])) > 0 )    
      {
        e1[i,j] <- 0
        
      }        
      
    }
    
} 

The runtime is very high. Appreciate any suggestions to improve the speed. Additional info: copying new values into the data frame is being done.

Thanks, Sandy

edit 2:

Sample data:

structure(list(`Sr no` = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 
12, 13, 14, 15, 16, 17, 18, 19), `2018-01` = c(0, 0, 0, 0, 0, 
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), `2018-02` = c(0, 0, 
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), `2018-03` = c(0, 
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), `2018-04` = c(0, 
0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), `2018-05` = c(0, 
0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0), `2018-06` = c(0, 
0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0), `2018-07` = c(0, 
0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0), `2018-08` = c(0, 
0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1), `2018-09` = c(0, 
0, 0, 1, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0), `2018-10` = c(1, 
0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1), `2018-11` = c(0, 
1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1), `2018-12` = c(1, 
0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0), `2019-01` = c(0, 
0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0), `2019-02` = c(0, 
0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0)), row.names = c(NA, 
-19L), class = c("tbl_df", "tbl", "data.frame"))

Answer 1

I think you can do this with matrix logic. Depends if you have enough RAM.

# creating fake data
# nc <- 300 # number of columns
nc <- 10 # for testing
nn <- 1e6 # rows
e <- sapply(1:nc, function(x) sample.int(2, nn, replace = T) - 1L) 
e <- as.data.frame(e)

row1 <- nrow(e)
colc <- ncol(e)
# note that:
3:colc-1
# isnt equal with:
3:(colc-1)

s <- 3:(colc-1) # I assume you meant this
e1 <- matrix(nrow = row1, ncol = length(s)) # empty resulting matrix
s1 <- sapply(s, function(j) rowSums(e[, 2:j])) # sum for each relevant i,j
s2 <- sapply(s, function(j) rowSums(e[, j:colc])) # sum for each relevant i,j

e2 <- as.matrix(e[, s]) # taking relevant columns of e

e1[s1 == 0] <- 0
e1[s1 > 0 &  e2 == 0 & s2 > 0] <- 1
e1[s1 > 0 &  e2 == 1 & s2 > 0] <- 0