#!/usr/bin/perl

while(<>) {
 @stuff=split(' ');

 if(/UQMD/){
 }
 elsif(/projectile:/){
  $protar=$_
 }
 elsif(/equation_of_state:/){
  $ecm=$stuff[5];
  $midy=log($ecm/0.938);
  $elab=$stuff[3];
  $plab=$stuff[7];
 }
 elsif(/event#/){
  $noe++                    # numbers of events: noe
 }
 else{
  if($#stuff==14){

   @x=@stuff[0..3];
   @p=@stuff[4..7];
   @id=@stuff[8..11];

   $mass=$id[0];
   $ityp=$id[1];
   $iz2=$id[2];
   $charge=$id[3];

   if ($ityp==27) {
   $noe1=$noe;
    print("lambda \n");
    print("Event", $noe1, "\n");
}

  if ($itype==27 && $noe1==$noe){
    print("match");

#
#   if ($ityp== 27) {
#   $noe2=$noe;
#    print("Event", $noe2, "\n");

#     $neo2=$neo;
#       if ($neo1== &neo2){
#     print("lambda \n");
#     print("Event",$neo2, "\n");

#    $pt=sqrt($p[1]*$p[1]+$p[2]*$p[2]);
#    $ipt=int($pt/$dpt);
#    $npim[$ipt]++;
# print("2 lambdas \n");

#
#hier würde ich jetzt gerne überprüfen ob die 27 zwei mal im gleichen event auftaucht
#

}
}
 }
  }

Deine Daten

my %event;
#...
$event{$eventname}++;
#...
if($event{$eventname}>=2){
# mach was
}

#!/usr/bin/perl
use strict;
use warnings;

my $noe;
while(<>) { 
my @stuff=split(' ');

 if(/UQMD/){
 }
 elsif(/projectile:/){
 my $protar=$_
 }
 elsif(/equation_of_state:/){
  my $ecm=$stuff[5];
  my $midy=log($ecm/0.938);
  my $elab=$stuff[3];
  my $plab=$stuff[7];
 }
 elsif(/event#/){
  $noe++                    # numbers of events: noe
 }      
 else{
  if($#stuff==14){ 

   my @x=@stuff[0..3];   
   my @p=@stuff[4..7];
   my @id=@stuff[8..11];

   my $mass=$id[0];
   my $ityp=$id[1];
   my $iz2=$id[2];
   my $charge=$id[3];

# ab hier steht folgende info zur verfuegung:

# stuff[0] = r_0    = $x[0]
# stuff[1] = r_x    = $x[1]
# stuff[2] = r_y    .
# stuff[3] = r_z    .
# stuff[4] = p_0    = $p[0]
# stuff[5] = p_x    = $p[1]
# stuff[6] = p_y    .
# stuff[7] = p_z    .
# stuff[8] = mass   = $id[0]
# stuff[9] = ityp   = $id[1]
# stuff[10]= iz2    = $id[2]
# stuff[11]= charge = $id[3]
my $noe1;

   if ($ityp==27) {
    $noe1=$noe;
    print("lambda \n");
    print("Event", $noe1, "\n");
   
#   if ($itype==27 && $noe1==$noe){ #hier wuerde ich gern suchen ob 27 nochmal vorkommt in diesem event
#     print("match");

#   }
   }
} 
 }
  }
 

UQMD   version:       20030   1000  20030  output_file  14
projectile:  (ityp, char)   49  -1   target:  (mass, char)  197  79 
transformation betas (NN,lab,pro)     0.0000000  0.1110044 -0.0794210
impact_parameter_real/min/max(fm):    0.00  0.00  0.00  total_cross_section(mbarn):       0.00
equation_of_state:    0  E_lab(GeV/u): 0.2407E-01  sqrt(s)(GeV): 0.2263E+01  p_lab(GeV/u): 0.2528E+00
event#         1 random seed:  1234262625 (fixed)  total_time(fm/c):      200 Delta(t)_O(fm/c):      200.000
op  0    0    0    0    0    0    0    0    0    0    0    0    0    0    0  
op  0    0    0    0    0    0    1    0    1    0    0    0    0    2    1  
op  0    0    0    1    1    0    0    0    0    0    0    0    0    1    0  
pa 0.1000E+01   0.5200E+00   0.2000E+01   0.3000E+00   0.0000E+00   0.3700E+00   0.0000E+00   0.9300E-01   0.3500E+00   0.2500E+00   0.0000E+00   0.5000E+00  
pa 0.2700E+00   0.4900E+00   0.2700E+00   0.1000E+01   0.1600E+01   0.8500E+00   0.1550E+01   0.0000E+00   0.0000E+00   0.0000E+00   0.0000E+00   0.0000E+00  
pa 0.9000E+00   0.5000E+02   0.1000E+01   0.1000E+01   0.1000E+01   0.1500E+01   0.1600E+01   0.0000E+00   0.2500E+01   0.1000E+00   0.3000E+01   0.2750E+00  
pa 0.4200E+00   0.1080E+01   0.8000E+00   0.5000E+00   0.0000E+00   0.5500E+00   0.5000E+01   0.8000E+00   0.5000E+00   0.8000E+06   0.1000E+01   0.2000E+01  
pvec: r0              rx              ry              rz              p0              px              py              pz              m          ityp 2i3 chg lcl#  ncl or 
 198 200
       1       1       0       0       0       0       0       0
  0.20000000E+03 -0.29270856E+01 -0.21151216E+01 -0.10648322E+02  0.95357633E+00 -0.29205595E-01 -0.38037133E-01 -0.28511840E+00  0.90868890E+00          1  1  1        0    0   0
  0.20000000E+03 -0.26733028E+01 -0.48575282E+01 -0.11135421E+02  0.93966054E+00 -0.16105977E+00 -0.78331655E-01 -0.14366491E+00  0.91117848E+00          1  1  1        0    0   0
  0.20000000E+03  0.17302826E+01 -0.19563007E+01 -0.59252391E+01  0.93977688E+00 -0.16357943E+00 -0.15714093E+00 -0.14424081E+00  0.90051300E+00          1  1  1        0    0   0
  0.20000000E+03  0.53763010E+01  0.40176612E+01 -0.96760700E+01  0.93947602E+00  0.89151978E-01  0.10288793E+00 -0.14219121E+00  0.91862008E+00          1  1  1        0    0   0
  0.20000000E+03  0.13783666E+01 -0.58041928E+00 -0.95032043E+01  0.93026380E+00 -0.17300076E+00  0.10975707E+00 -0.48033855E-01  0.90614989E+00          1  1  1        0    0   0

#!/usr/bin/perl
use strict;
use warnings;

# Ein Hash mit den Eventnamen als Schlüssel.
# die Werte sind Zähler,
# welche die Häfigkeit des Auftreten der Events zählen.
my %events;

# Geammtanzahl der Events
my $noe;

while(<>) { 
my @stuff=split(' ');

 if(/UQMD/){
 }
 elsif(/projectile:/){
 my $protar=$_
 }
 elsif(/equation_of_state:/){
  my $ecm=$stuff[5];
  my $midy=log($ecm/0.938);
  my $elab=$stuff[3];
  my $plab=$stuff[7];
 }
 elsif(/event#/){
  $noe++                    # numbers of events: noe
 }      
 else{
  if($#stuff==14){ 

   my @x=@stuff[0..3];   
   my @p=@stuff[4..7];
   my @id=@stuff[8..11];

   my $mass=$id[0];
   my $ityp=$id[1];
   my $iz2=$id[2];
   my $charge=$id[3];

# ab hier steht folgende info zur verfuegung:

# stuff[0] = r_0    = $x[0]
# stuff[1] = r_x    = $x[1]
# stuff[2] = r_y    .
# stuff[3] = r_z    .
# stuff[4] = p_0    = $p[0]
# stuff[5] = p_x    = $p[1]
# stuff[6] = p_y    .
# stuff[7] = p_z    .
# stuff[8] = mass   = $id[0]
# stuff[9] = ityp   = $id[1]
# stuff[10]= iz2    = $id[2]
# stuff[11]= charge = $id[3]

   # Events eines bestimmten Typs zählen
   $event{$itype}++;

   if ($ityp==27) {
    print("lambda \n");
    print("Event", $noe, "\n");
    # Wenn der event des Typs "27" mindestens zwei mal aufgetaucht ist...
    if ($event{27} >= 2){
      print("match");
     # es könnte sinnvoll sein den zähler wieder zurück zu setzen,
     # oder die bedingung auf ==2 zu setzen.
     # Aber ich weiss nicht genug über die Logick um dir da zu helfen
    }
   }
  } 
 }
}

#!/usr/bin/perl
use strict;
use warnings;

#event 27 zählen
my count_event_27=0;

# Geammtanzahl der Events
my $noe;

while(<>) { 
my @stuff=split(' ');

 if(/UQMD/){
 }
 elsif(/projectile:/){
 my $protar=$_
 }
 elsif(/equation_of_state:/){
  my $ecm=$stuff[5];
  my $midy=log($ecm/0.938);
  my $elab=$stuff[3];
  my $plab=$stuff[7];
 }
 elsif(/event#/){
  $noe++                    # numbers of events: noe
 }      
 else{
  if($#stuff==14){ 

   my @x=@stuff[0..3];   
   my @p=@stuff[4..7];
   my @id=@stuff[8..11];

   my $mass=$id[0];
   my $ityp=$id[1];
   my $iz2=$id[2];
   my $charge=$id[3];

# ab hier steht folgende info zur verfuegung:

# stuff[0] = r_0    = $x[0]
# stuff[1] = r_x    = $x[1]
# stuff[2] = r_y    .
# stuff[3] = r_z    .
# stuff[4] = p_0    = $p[0]
# stuff[5] = p_x    = $p[1]
# stuff[6] = p_y    .
# stuff[7] = p_z    .
# stuff[8] = mass   = $id[0]
# stuff[9] = ityp   = $id[1]
# stuff[10]= iz2    = $id[2]
# stuff[11]= charge = $id[3]

   if ($ityp==27) {
    $count_event_27++;
    print("lambda \n");
    print("Event", $noe, "\n");
    # Wenn der event des Typs "27" mindestens zwei mal aufgetaucht ist...
    if ($count_event_27++; >= 2){
      print("match");
     # es könnte sinnvoll sein den zähler wieder zurück zu setzen,
     # oder die bedingung auf ==2 zu setzen.
     # Aber ich weiss nicht genug über die Logick um dir da zu helfen
    }
   }
  } 
 }
}