Question

I have the following test script

 /^[^a-zA-Z0-9]/  {
    DATEd[$3] = $1
    } 
   END { 
        print "        \"data\": ["
        for (i = 0 ; i <= 5; i ++ ) {
            { print "            [" i ", \"" DATEd[i] "\"],"}
        }
        print "        ]"
}

And are reading from this text file

2011-01-22 22:12 P16A22_110114072915 22 1312 75 13.55 1399
2011-01-22 22:12 P16A22_110114072915 22 1312 75 13.55 1399 
2011-01-22 22:12 P16A22_110114072915 22 1312 75 13.55 1399 
2011-01-22 22:12 P16A22_110114072915 22 1312 75 13.55 1399
2011-01-22 22:12 P16A22_110114072915 22 1312 75 13.55 1399 
2011-01-22 22:12 P16A22_110114072915 22 1312 75 13.55 1399

But it doesn’t print out what I want it to, I want it to print out

    "data": [
        [0, "2011-01-22"],
        [1, "2011-01-22"],
        [2, "2011-01-22"],
        [3, "2011-01-22"],
        [4, "2011-01-22"],
        [5, "2011-01-22"],
    ]

When it in fact are only printing out

"data": [
    [0, ""],
    [1, ""],
    [2, ""],
    [3, ""],
    [4, ""],
    [5, ""],
]

So why is “DATEd[$3] = $1” empty?

Also how do I check the length of an array?
DATEd.length doesn’t work in this case.

Thanks

EDIT_______________________________________________

So from the help of @Fredrik and @geekosaur I have come somewhere with this, now to some last questions

1) The script now looks like this

 /[a-zA-Z0-9]/  {
    DATEd[NR-1] = $1
    } 
   END { 
        print "        \"data\": ["

        for (i in DATEd) {
            { print "            [" i ", \"" DATEd[i] "\"],"}
        }
        print "        ]"
}

And gives the following output

"data": [
    [4, "2011-01-26"],
    [5, "2011-01-27"],
    [6, "2011-01-28"],
    [0, "2011-01-22"],
    [1, "2011-01-23"],
    [2, "2011-01-24"],
    [3, "2011-01-25"],
]

But I want it to look like this

"data": [
[0, "2011-01-22"],
[1, "2011-01-23"],
[2, "2011-01-24"],
[3, "2011-01-25"],
[4, "2011-01-26"],
[5, "2011-01-27"],
[6, "2011-01-28"]
]

I.E be sorted and removing the last ‘,’ character before the final closing ‘]’ character. Is this possible to accieve in a easy way? =)

Thanks =)

EDIT 3 Final Outcome_______________________________________

Used a combination of @geekosaur and @Fredrik contribution’s =)

{
    DATEd[NR-1] = $1; len++
}
   END { 
        print "        \"data\": ["

        #for (i in DATEd) {
        for (i = 0 ; i <= len-1; i ++ ) {
            { print "            [" i ", \"" DATEd[i] "\"],"}
        }
        print "        ]"
}

Answer 1

As a start, your regex is wrong, /^[^a-zA-Z0-9]/ means to match the start of a line and NOT followed by a letter or a number. None of the lines have that setup, hence, your array DATe is empty.

Secondly, your array is not indexed by 0-5 but instead the content of $3 (if you fix your regex)

There is no built in function to get the length of an array, but it’s simple to implement one.

Array example

function array_length(a) {
    for (i in a) n++
    return n
}

{
    DATEd[NR] = $1
}
END {
    for (i in DATEd) {
        print i, DATEd[i]
    }
    print "Number of items", array_length(DATEd)

    # copy indices
    j = 1
    for (i in DATEd) {
        ind[j] = i    # index value becomes element value
        j++
    }
    n = asort(ind)    # index values are now sorted
    for (i = 1; i <= n; i++)
        print i, DATEd[ind[i]]
}

Gives:

4 2011-01-22
5 2011-01-22
6 2011-01-22
1 2011-01-22
2 2011-01-22
3 2011-01-22
Number of items 6
1 2011-01-22
2 2011-01-22
3 2011-01-22
4 2011-01-22
5 2011-01-22
6 2011-01-22

See the gnu awk manual for an description of arrays

Too loop through all elements of an array, use this construct (see link above)

 for (var in array)
   body