<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii"> <TITLE>Message</TITLE> <META content="MSHTML 6.00.2900.2722" name=GENERATOR></HEAD> <BODY> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>Hi  </SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>I have just entered the exciting field of detector simulation using GATE.</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>I am using ROOT for analysis of Gate.root data. </SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT><FONT face=Arial size=2><SPAN class=465031019-02092005>First of all, I like to thank all those who have made it possible for these wonderful software packages to be freely available for researchers all over the world.</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>Now, I have a  question about displaying histogram using ROOT.</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>The Draw() method provides a very easy way to display a histogram and has a very neat implementation of a selection option.</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>e.g.,  Singles->Draw("globalPosX","energy>0.1");  Display those Singles with energy less than 0.1 Mev.</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>However, the easy selection method does not seem to extend to string operation. For example, if I want to display the same globalPosX for those Singles that had at least Compton interaction in the SPECThead, I thought the following line might work, it it did not,</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>  Singles->Draw("globalPosX","!strcmp(comptVolName,"SPECTHead"));  To display those Singles with a Compton interaction in the SPECThead.</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>However, the 'comptVolName' is not recognized by ROOT, while globalPosX is.  </SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>Can some one point out what was wrong with the above line?</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>Is there a correct and similarly easy way to display a variable with logical operation on strings as a selection method?</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>I understand that an alternative way is to use the Get Entry() method in a loop. </SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>If using GetEntry() is the only way possible to display a histogram when selection is based on comparison of strings, please tell me, so I won't keep looking for an easy way out.</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>Thanks in advance.</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>Tim</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>   </SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT><FONT face=Arial size=2><SPAN class=465031019-02092005> </SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=465031019-02092005>  </SPAN></FONT></DIV></BODY></HTML>