Selecting the components of a vector inside an if statement inside a for loop-CodePudding

I'm trying to check if the absolute value of each component of the vector differenza inside a for loop is greater than 0.001 by using if statements, but it seems that I'm not selecting a component because I got the error:

Warning in if (abs(differenza[i]) > 0.001) { :
  the condition has length > 1 and only the first element will be used

Which kind of mistake did I make?

lambda = 10
n = 10
p = lambda/n
K = 10
x = 0:K

denbinom = dbinom(x, n, p)
denpois = dpois(x, lambda)

differenza = denbinom - denpois

for (i in differenza) {
  if (abs(differenza[i]) > 0.001) {
    cat("Componente", i > 0.001, "\n")
  }
  if (abs(differenza[i]) <= 0.001) {
    cat("Componente", i, "ok")
  }
}

CodePudding user response：

What you need is to use seq_along():

for (i in seq_along(differenza)) {
  if (abs(differenza[i]) > 0.001) {
    cat("Componente", i > 0.001, "\n")
  }
  if (abs(differenza[i]) <= 0.001) {
    cat("Componente", i, "ok")
  }
}

You can also simplify your if statement:

for (i in seq_along(differenza)) {
  if (abs(differenza[i]) > 0.001) {
    cat("Componente", TRUE, "\n")
  }else {
    cat("Componente", i, "ok", "\n")
  }
}

Edit

If you wish to print the real values of i:

for (i in seq_along(differenza)) {
  if (abs(differenza[i]) > 0.001) {
    cat("Componente", i,  "> 0.001", "\n")
  }
  if (abs(differenza[i]) <= 0.001) {
    cat("Componente", i, "ok", "\n")
  }
}