Is not a ROOT problem. The code that was been used did not check for the
array counter before trying to read a value, therefore the value present
was the memory resident value of some previous event.
Ricardo
Rene Brun wrote:
>Hi Mircea,
>
>Which version are you using? When reading (normal or a la MakeClass)
>the array counter is set to 0 if the number of array elements was 0.
>
>Rene Brun
>
>On
>Fri, 28 Feb 2003, Mircea Coca wrote:
>
>
>
>> Hi,
>>
>> We found the problem: not checking the number of entries
>>in the array; root doesn't initialize the array element to some
>>nonsense number every time reads an event. So if the previous event had 2
>>electrons and the current event has only one, then the second entry in the
>>electron array has the second electron values from the previous
>>event...The weakness of using MakeClass.
>>
>> Mircea
>>
>>On Fri, 28 Feb 2003, Jedong Lee wrote:
>>
>>
>>
>>>I noticed et2 of j=164 and j=165 were the same. It was a length-of-array
>>>problem, not a bug of CopyTree().
>>>I realize CopyTree() was smarter than I am.
>>>
>>>- Jedong
>>>
>>>On Fri, 28 Feb 2003, Jedong Lee wrote:
>>>
>>>
>>>
>>>>Hello,
>>>>
>>>>I am stripping off an ntuple with command like this: (ROOT 3.05/00)
>>>>
>>>> TTree *small = mmm.fChain->CopyTree("Et[0]>20&&Et[1]>20")
>>>>
>>>>By the way, the resulting file contains less events than I expected.
>>>>I compared the entries and found that not all the events
>>>>that pass the criteria are written to the target file.
>>>>
>>>>This seems to be happening whenever the event(entry = i) passes
>>>>the cut and event(entry = i+x) also passes, and x is small number..
>>>>
>>>>This is the list of variables in two files:
>>>>( j=164 and j=165 passes the cut, only j=164 survived.
>>>> Out of j=175,177,178,179, j=175 and j=178 survived.
>>>> Out of j=301,302, j=301 survived.)
>>>>
>>>>Original file: (showing the events that passes the cut)
>>>>
>>>>j 8 et1 101.701 et2 37.4808
>>>>j 10 et1 39.8504 et2 27.9597
>>>>j 28 et1 43.283 et2 37.779
>>>>j 84 et1 45.18 et2 27.6098
>>>>j 86 et1 40.8786 et2 20.0176
>>>>j 141 et1 37.3549 et2 22.055
>>>>j 158 et1 32.8841 et2 20.5765
>>>>j 164 et1 46.0031 et2 29.4996
>>>>j 165 et1 38.1034 et2 29.4996
>>>>j 175 et1 70.7513 et2 31.3695
>>>>j 177 et1 32.906 et2 31.3695
>>>>j 178 et1 32.8016 et2 24.8853
>>>>j 179 et1 22.3331 et2 24.8853
>>>>j 216 et1 151.5 et2 91.1525
>>>>j 246 et1 26.6626 et2 20.8906
>>>>j 257 et1 121.573 et2 72.1682
>>>>j 267 et1 36.5081 et2 23.0727
>>>>j 301 et1 40.4186 et2 36.0574
>>>>j 302 et1 29.8817 et2 36.0574
>>>>j 334 et1 59.1586 et2 37.6737
>>>> .
>>>> .
>>>> .
>>>>
>>>>Target file: (all the events in the target)
>>>>
>>>>j 0 et1 101.701 et2 37.4808
>>>>j 1 et1 39.8504 et2 27.9597
>>>>j 2 et1 43.283 et2 37.779
>>>>j 3 et1 45.18 et2 27.6098
>>>>j 4 et1 40.8786 et2 20.0176
>>>>j 5 et1 37.3549 et2 22.055
>>>>j 6 et1 32.8841 et2 20.5765
>>>>j 7 et1 46.0031 et2 29.4996
>>>>j 8 et1 70.7513 et2 31.3695
>>>>j 9 et1 32.8016 et2 24.8853
>>>>j 10 et1 151.5 et2 91.1525
>>>>j 11 et1 26.6626 et2 20.8906
>>>>j 12 et1 121.573 et2 72.1682
>>>>j 13 et1 36.5081 et2 23.0727
>>>>j 14 et1 40.4186 et2 36.0574
>>>>j 15 et1 59.1586 et2 37.6737
>>>> .
>>>> .
>>>> .
>>>>
>>>>Best,
>>>>Jedong
>>>>
>>>>
>>>>
>>>>
>
>
>
--
--------------------------------------------------------------------
Ricardo Eusebi
High Energy Physics
University of Rochester
Fermilab, (630) 840 8622
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