I hope this toy example gives an idea to understand the problems that you are facing now. Please see the below:

# 1. Create an empty list

> A <- list()
> A
list()

# 2. Add the first component (vector with two elements).

> A[[1]] <- c(2,6)
> A
[[1]]
[1] 2 6

# 3. Now, add the third component (vector with three elements).
# I did not add the second component INTENTIONALLY.

> A[[3]] <- c(1,3,2)
> A
[[1]]
[1] 2 6

[[2]]
NULL

[[3]]
[1] 1 3 2

# I see the second element has NULL value.
# You can apply 'is.null()' to this second component.

> is.null(A[[2]])
[1] TRUE

# However, you will see the error as below if 'is.null()' is used for the fourth component.

> is.null(A[[4]])
Error in A[[4]] : subscript out of bounds

# Why?  It is because the list 'A' has only three components.

> length(A)
[1] 3
>

I hope this helps.  I would appreciate if you DO READ the posting guide.

Chel Hee Lee

On 1/20/2015 9:30 AM, Ragia Ibrahim wrote:
Hello,
kindly ,
how to catch this Error
Error in A[[i]] : subscript out of bounds
and check that the list is empty is.null( A[[i]] ) do no twork
  thanks in advance
R.I
                                        
        [[alternative HTML version deleted]]

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