see ?is.null e.g. if( is.null(sub_grp_whr_cls_data[sbgrp_no, 1]) ) { your code }
Moumita Das wrote: > Hi friends, > Please help me with this bug. > > *Bug in my code:* > > In this variable sub_grp_whr_cls_data[sbgrp_no,1] I store the where > clause.every sub group has a where condition linked with it. > > Database1 > > > Where clause was not found for a particular subgroup, > sub_grp_whr_cls_data[sbgrp_no,1] value was NULL > > So the condition (*sub_grp_whr_cls_data[sbgrp_no,1]=="NULL" || > sub_grp_whr_cls_data[sbgrp_no,1]==""*) should evaluate to TRUE ,but it > evaluated to NA > > So the if block where I used the the condition threw error > > If(*sub_grp_whr_cls_data[sbgrp_no,1]=="NULL" || > sub_grp_whr_cls_data[sbgrp_no,1]==""*) > > i.e if(NA) > > Error:-- > > Error in if (sub_grp_whr_cls_data[sbgrp_no, 1] == "NULL" || > sub_grp_whr_cls_data[sbgrp_no, : > > missing value where TRUE/FALSE needed > > Comments:-- but when there ‘s no where clause value the condition > (sub_grp_whr_cls_data[sbgrp_no,1]=="NULL" > ||sub_grp_whr_cls_data[sbgrp_no,1]=="") should automatically evaluate to * > TRUE* > > > > Database2 > > Where clause was found for a particular subgroup > > The condition (sub_grp_whr_cls_data[sbgrp_no,1]=="NULL" > ||sub_grp_whr_cls_data[sbgrp_no,1]=="") evaluated to FALSE > > So if (sub_grp_whr_cls_data[sbgrp_no,1]=="NULL" > ||sub_grp_whr_cls_data[sbgrp_no,1]=="") is > > If (FALSE) ,control goes to the else part. > > This is exactly what is expected of the program. > > *QUERY:-- **If the condition evaluates to FALSE when a where condition is > available why doesn’t it evaluate to TRUE when a where condition available > is NULL or no where condition is available.* > > Here I have taken the example of two databases where I tried to get the > where clause for subgroup 1.In case of Database1 it was not available in > case of Databse2 it was available.But the problem may appear for the same > database also, when where clause is available for say one subgroup and not > for the other. > > > > ------------------------------------------------------------------------ > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Matthias Burger Project Manager/ Biostatistician Epigenomics AG Kleine Praesidentenstr. 1 10178 Berlin, Germany phone:+49-30-24345-0 fax:+49-30-24345-555 http://www.epigenomics.com matthias.bur...@epigenomics.com -- Epigenomics AG Berlin Amtsgericht Charlottenburg HRB 75861 Vorstand: Geert Nygaard (CEO/Vorsitzender) Oliver Schacht PhD (CFO) Aufsichtsrat: Prof. Dr. Dr. hc. Rolf Krebs (Chairman/Vorsitzender) ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.