[R] corrgram

[Rui Barradas]

Hello,

You should say which package you are getting 'corrgram' from. I'll 
assume it's from package corrgram.

The answer to your question is not in the help page but part of it is, 
it says it calls function 'col.corrgram'.
And R is open source so a quick look at the package *.R sources (only 
one file, to make it simpler) shows that 'col.corrgram' uses the color 
interpolation function colorRampPalette() from recomended package 
grDevices with argument 'colors' set to

c("red","salmon","white","royalblue","navy")

In fact, 'col.corrgram' is a one liner, that creates a color palette 
with number of colors equal to 'ncol '.
The functions that call 'col.corrgram' always set ncol <- 14 prior to 
creating the palette, so what you have is the interval [-1, 1] mapped to 
a set of 14 colors ranging from red to navy blue.

The manual does say that if users wants to, they can change 
'col.corrgram'. It seems to be the best way of changing 'corrgram' 
default set of colors. The other one is to change the setting of 'ncol' 
in three different places.

Have fun.

Rui Barradas

Em 28-08-2012 08:54, paladini escreveu:
> Hello,
> are there fixed threshold values for the changes between different 
> shades of blue in the corrgram?
> Or is a chang  relative depending on the data?
> I didnt get it in manual.
>
> Thank you very much, best regards
>
> Claudia
>
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