Roy,
I have no idea what you're actually trying to do here, but
it looks like there would be a more natural R'ish way if
you're concerned about grouping consecutive elements of 'a'.
At any rate, within your while loop, you're incrementing n by
1, and eventually n will be 10, which will be transformed to
11 when you add 1 to it, and a[11] will be NA, thus the error
you receive...
Roy Mathew wrote:
Dear R-users,
This is a loop which is part of a bigger script. I managed to isolate the
error in this loop and simplified it to the bare minimum and made it
self-contained.
a<-c(2,3,4,5,5,5,6,6,6,7)
for(n in 1:10)
{
print(paste("n: ",n))
z1<-a[n]
#make a list container
ldata<-list()
t=1
while(z1==a[n])
{
#add dataframes to list
ldata[[t]]<-paste("hello")
n=n+1
t=t+1
}
print("------End of while loop-------")
for(y in 1:length(ldata))
{
print(ldata[[y]])
}
print(paste("n: ",n))
print("******End of for loop********")
}
This script has a vector "a", for-loop, and a nested while-loop.
The for-loop runs from 1 to length of a. At every number of a, it enters the
while-loop and a hello is saved into list ldata.
If the next number in the vector a is a different number from previous then
the while-loop is exited and saved hello is printed.
If the next number in vector a is same as before then it loops inside the
while-loop and several hellos are printed together.
Then run-time error is
Error in while (z1 == a[n]) { : missing value where TRUE/FALSE needed
Thats because an NA creeps in somewhere. The problem can be seen far before
that. The full output from the run is below.
A lot of stuff was printed to help with the debugging. At n=4, there are
three repeats of 5, therefore hello is printed 3 times. n then becomes 7.
Then when the for-loop returns to top, n miraculously becomes 5. Hows
that!!?? Then on, everything goes wrong. I cannot figure out the problem.
[1] "n: 1"
[1] "------End of while loop-------"
[1] "hello"
[1] "n: 2"
[1] "******End of for loop********"
[1] "n: 2"
[1] "------End of while loop-------"
[1] "hello"
[1] "n: 3"
[1] "******End of for loop********"
[1] "n: 3"
[1] "------End of while loop-------"
[1] "hello"
[1] "n: 4"
[1] "******End of for loop********"
[1] "n: 4"
[1] "------End of while loop-------"
[1] "hello"
[1] "hello"
[1] "hello"
[1] "n: 7"
[1] "******End of for loop********"
[1] "n: 5"
[1] "------End of while loop-------"
[1] "hello"
[1] "hello"
[1] "n: 7"
[1] "******End of for loop********"
[1] "n: 6"
[1] "------End of while loop-------"
[1] "hello"
[1] "n: 7"
[1] "******End of for loop********"
[1] "n: 7"
[1] "------End of while loop-------"
[1] "hello"
[1] "hello"
[1] "hello"
[1] "n: 10"
[1] "******End of for loop********"
[1] "n: 8"
[1] "------End of while loop-------"
[1] "hello"
[1] "hello"
[1] "n: 10"
[1] "******End of for loop********"
[1] "n: 9"
[1] "------End of while loop-------"
[1] "hello"
[1] "n: 10"
[1] "******End of for loop********"
[1] "n: 10"
Error in while (z1 == a[n]) { : missing value where TRUE/FALSE needed
Mr Stuck-up.....
Thanks for any help.
Roy
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