Sunday, October 5, 2008

Validating a DRGFilt Control File


I find the DRGFilt control file format kind of hard to understand. How can I be sure that I got it right?


We hear you: the control file format is showing its age: it was derived from a format that originated on punch cards (!).

We use the following Perl script to validate our control files in-house:

Sample usage
In the examples below, replace "control-file" with the name of the control file you are validating, and "data-file" with the name of the data file you are running against. For extra credit, replace "pt-id" with the patient, claim or record ID you are looking for.

  • perl control-file < data-file | more
  • head -20 data-file | perl control-file | more
  • fgrep pt-id data-file | perl control-file
  • perl.exe control-file < data-file | more
  • perl.exe control-file < data-file > output.txt

Sample Perl Code

# - program to check a control file

my($sgl,$dxl,$recLen,%h) = Load(shift(@ARGV));

while (defined(my $l = <>)) {
    $l =~ s/\r|\n//g;
    # pad out input with astericks if too short
    while (length($l) < $recLen) { $l .= '*'; }

    my $output = "";
    foreach my $key (sort (keys %h)) {
    my $ref = $h{$key};
    my($name,$off,$len) = @$ref;

    my $val = substr($l,$off,$len);
    $output .= sprintf("%4.4s@%3d for %2d:",$name,$off,$len);

    if ($name =~ /^(dx|surg)$/i) {
        $output .= AddBar($val, ($name =~ /dx/i)? $dxl : $sgl);
    } else {
        $output .= $val;

    $output .= "\n";
    print $output,"\n";

sub AddBar {
    my $val = shift;
    my $len = shift;

    my $inLen = length($val);
    my @f = ();

    for (my $i = 0; $i < $inLen; $i += $len) {

    return join('|',@f);

sub Load {
    my $fname = shift;

    my %h;  # keyed by offset, value is name
    my($dxl,$sgl) = (5,4);
    my $recLen = 0;

    open(FILE,$fname) || die "Could not open '$fname': $!";
    while (defined(my $l = <FILE>)) {
    next unless ($l =~ /^[a-zA-Z]/);
        #age  000 03
    my($name,$offset,$length) = unpack("a4xa3xa2",$l);

    if ($name =~ /sgl/i) {
        $sgl = $length;
    if ($name =~ /dxl/i) {
        $dxl = $length;
    if ($name =~ /poa/i) {
        $poa = $length;
    if ($name =~ /exmp/i) {
        $exempt = $length;

    my $key = sprintf("%03d",$offset);
    my $ref = [ $name, $offset, $length ];
    foreach my $el (@$ref) { $el =~ s/^\s+|\s+$//g; }
    $h{$key} = $ref;


    # figure out end of record: max offset + length
    my ($max) = (reverse (sort keys %h));
    my $ref = $h{$max};
    my $recLen = $$ref[1] + $$ref[2];

    return ($sgl,$dxl,$recLen,%h);
# eof

Friday, October 3, 2008

F26 Released

Our support for version 26 of the US Federal DRG assignment algorithm, active as of October 1st 2008, has just been released.

F26 DRGFilt Control File

New this year: "poa", "exmp".

age  000 03
sex  003 01
ds   004 02
dxl  000 08
poa  000 07
dx   023 96
sgl  000 07
surg 223 98
exmp 006 01
# these are written out by us
drg  607 03
mdc  610 02
rc   612 02

Thursday, January 24, 2008

PHP Shared Object


We recently purchased the PHP shared object from you guys and are having problems getting it running. We are using PHP 5.2.5 on Red Hat Linux 9, and are getting the following error when we try to dynamically link your library:

Warning: dl(): unable to load dynamic library './' -
undefined symbol: zend_list_find

Any ideas? Let me know if you need more info or if I need to be addressing this question to RTR. Also, if we can't get this to work fairly easily, would we have the option of "trading" this PHP .so for your C callable object?


As I understand it, things are supposed to work like this:

 - you put in a place in your file system that is both
   - readable by your web server
   - not accessible by the world or the world can steal it

 - you use the dl() primative in PHP to load the extension, like so:

    if (!extension_loaded('mhdrg')) {
        if (!dl('')) {  // this should be in a protected directory
When I deliberately move on our test system, I get the following error:

Warning: Unable to load dynamic library './' - ./ cannot open shared object file: No such file or directory in /home/mnh/public_html/PHP/tryit.php on line 5

So I am guessing that wherever you have put is not readable by the user your web server runs as. Have you put in the same document directory as your document? If not, you could trying putting tryit.php and in the same document directory and confirming that tryit.php works on your systems.

That said, we would be happy to exchange your PHP shared object for a C-callable object if that works better for you.