Confusion of CopyTree

[realTay_John]

Hi experts,

I am using copytree(cut) to select some entries:

# the total entries in the file is 327246.
# Then I use follow command to select some entries:
nt_fom = tfom.CopyTree("mass<160", "", 200000)
# but it just return 90000 entries

# If I use follow command(that is remove kmaxentries constrain):
nt_fom = tfom.CopyTree("mass<160")
# it returns 140000 entries.

I want to select all the entries with mass<160
Which one command is right?

[couet]

Does the explanation in the ref guide helps you ? It seems clear enough.

[realTay_John]

Thanks for this answer. In fact, I found the page Tree::CopyTree to see what kMaxEntries means, but it doesn’t explain.

[realTay_John]

I am confused because there are many classes share same method. I dont know which one should I really find to know its(method’s) detail usage.

[couet]

It is like TTree::Draw. If you do not specify this parameter all the tree is scanned:

nentries	The number of entries to process (default is all)

[realTay_John]

ok. thanks for your further explanation.