Remove last entry of vector if zero-CodePudding

How can I make sure that the last entry of the vector is non-zero?

# Current output
polycoefs("-x^{3} 3x^5-x-3x^3- 3x^5 - 1")
x^0 x^1 x^2 x^3 x^4 x^5 
 -1  -1   0  -4   0   0

# Intended output 
polycoefs("-x^{3} 3x^5-x-3x^3- 3x^5 - 1")
x^0 x^1 x^2 x^3 
 -1  -1   0  -4

CodePudding user response：

If:

result = polycoefs("-x^{3} 3x^5-x-3x^3- 3x^5 - 1")
x^0 x^1 x^2 x^3 x^4 x^5 
 -1  -1   0  -4   0   0

If you want to make the last entry non-zero:

while(tail(result,1) == 0){
  result = result[-length(result)]
}

That:

> result
x^0 x^1 x^2 x^3 
 -1  -1   0  -4

You can add it to your function just before returning result.

If you want to remove all 0s you can do (Idk why keeping x2):

> result[-which(result == 0, arr.ind=TRUE)]
x^0 x^1 x^3 
 -1  -1  -4