# problem with corrgram function

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## problem with corrgram function

 Dear list, I have a problem with the "corrgram" function. It does not seem to "color" large negative correlations, while the same correlation, if positive, provides no problems. Is this a bug?         require(corrgram)         a = seq(1,100)         b = -jitter(seq(1,100), 80)         cor(a,b) # r about -.96         c=as.data.frame(cbind(a,b))         corrgram(c, order=NULL, lower.panel=panel.pie,upper.panel=NULL, text.panel=panel.txt) # no color                 c\$b = -1*c\$b # flip direction of correlation         cor(c\$a, c\$b) # r now about +.96         corrgram(c, order=NULL, lower.panel=panel.pie,upper.panel=NULL, text.panel=panel.txt) #no problem with color. Thanks! ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
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## Re: problem with corrgram function

 yes it is. and a correlation of 0 isn't exactly white (#FFFFFF) either. have a look at the panel.pie function. the crucial part is     ncol <- 14     pal <- col.corrgram(ncol)     col.ind <- round(ncol * (corr + 1)/2) so an correlation near -1 maps to an index 0, which isn't a proper index in R. Alter these lines to      ncol <- 15 #so 0 becomes "#FFFFFF"      pal <- col.corrgram(ncol)      col.ind <- round((ncol-1) * (corr + 1)/2)+1 hth. Am 28.06.2011 13:11, schrieb Niels Janssen: > Dear list, > > I have a problem with the "corrgram" function. It does not seem to > "color" large negative correlations, while the same correlation, if > positive, provides no problems. Is this a bug? > >     require(corrgram)   >     a = seq(1,100) >     b = -jitter(seq(1,100), 80) >     cor(a,b) # r about -.96 >     c=as.data.frame(cbind(a,b)) >     corrgram(c, order=NULL, lower.panel=panel.pie,upper.panel=NULL, > text.panel=panel.txt) # no color >     >     c\$b = -1*c\$b # flip direction of correlation >     cor(c\$a, c\$b) # r now about +.96 >     corrgram(c, order=NULL, lower.panel=panel.pie,upper.panel=NULL, > text.panel=panel.txt) #no problem with color. > > Thanks! > > ______________________________________________ > [hidden email] 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. -- Eik Vettorazzi Department of Medical Biometry and Epidemiology University Medical Center Hamburg-Eppendorf Martinistr. 52 20246 Hamburg T ++49/40/7410-58243 F ++49/40/7410-57790 ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.