There doesn't seem to be any examples of 'next' usage in the control flow help page. I'd like it to skip to the next iteration based on a condition within the script.
Using the example below, let's say I don't want it to print, unless x[i] > 5
, the expected output would be 5 through 10 on screen:
x <- 1:100
for(i in 1:10) {
# next(x[i] < 5) # Just for conceptualizing my question.
print(x[i])
}
How would I go about implementing the use of next
to accomplish something like what's shown above?
next statement is an iterative, incremental loop statement used to repeat a sequence of statements for a specific number of occurrences. A for... next loop executes a set of statements for successive values of a variable until a limiting value is encountered.
In computer programming, control flow or flow of control is the order function calls, instructions, and statements are executed or evaluated when a program is running. Many programming languages have what are called control flow statements, which determine what section of code is run in a program at any time.
There are two primary tools of control flow: choices and loops. Choices, like if statements and switch() calls, allow you to run different code depending on the input. Loops, like for and while , allow you to repeatedly run code, typically with changing options.
I will give you a complete example and a 'yes' but I am unsure what your questions is:
R> for (i in 1:10) {
+ if (i < 5) next
+ print(i)
+ }
[1] 5
[1] 6
[1] 7
[1] 8
[1] 9
[1] 10
R>
To make this work, you need to test whether x < 5
and, if it is, go to next
. next
will, in turn (to quote the help page), "[halt] the processing of the current iteration and [advance] the looping index", starting back through the loop again.
x <- 1:100
for(i in 1:10) {
if(x[i] < 5) next
print(x[i])
}
[1] 5
[1] 6
[1] 7
[1] 8
[1] 9
[1] 10
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