CODEWITHSUNDEEP
r
Dea12
Dea12

Reputation: 5

How to conditionally remove rows of a matrix in a loop

I have this matrix named d.

This is the d matrix

     V1    V2       V3       V4
1    I     14.06863 11.50424 333173.1
2    N     14.50265 11.89501 387709.7
3    I     14.55234 11.95746 402124.0
4    I     14.78606 12.14149 453059.3
5    N     15.16970 12.51004 496142.1
6    D     14.41104 11.81296 539661.3
7    D     14.86976 12.23968 603475.4

I find the 

d$Delta_Cost <- c(0, diff(d[, 4]))
d$Delta_LY <- c(0, diff(d[, 2]))

I need to loop through the matrix and remove the row that fulfills this condition

Delta_Cost>0 & Delta_LY<0

But i don't know how to do this in R.

Thank you!

Upvotes: 0

Views: 599

Answers (1)

Richie Cotton
Richie Cotton

Reputation: 121057

Here's a reproducible version of your data:

d <- read.table(
  text = "
     V1    V2       V3       V4
1    I     14.06863 11.50424 333173.1
2    N     14.50265 11.89501 387709.7
3    I     14.55234 11.95746 402124.0
4    I     14.78606 12.14149 453059.3
5    N     15.16970 12.51004 496142.1
6    D     14.41104 11.81296 539661.3
7    D     14.86976 12.23968 603475.4",
  header = TRUE
)

Since you want the contents of the loop to be run at least once, you want a repeat loop rather han a whileloop. to_remove is a logical vector which is TRUE whenever you want to remove the row. If there are no rows to remove, if(!any(to_remove)), we break out of the loop.

repeat
{    
  Delta_Cost <- c(0, diff(d[, 4]))
  Delta_LY <- c(0, diff(d[, 2]))    
  to_remove <- Delta_Cost > 0 & Delta_LY < 0 
  if(!any(to_remove))
  {
    break
  }
  d <- d[!to_remove, ]
}
d
##   V1       V2       V3       V4
## 1  I 14.06863 11.50424 333173.1
## 2  N 14.50265 11.89501 387709.7
## 3  I 14.55234 11.95746 402124.0
## 4  I 14.78606 12.14149 453059.3
## 5  N 15.16970 12.51004 496142.1

Upvotes: 1

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