Customize Color Using Lighter in BarChart

Please Consider :

 dalist = {{901, 503, 522, 1305}, {910, 512, 477, 1260}, 
           {847, 459, 556, 1275}, {799, 517, 527, 1197}}

 cogColors = {RGBColor[0, 0, 1], RGBColor[1, 0, 0], RGBColor[0, 1, 0], RGBColor[1, 1, 0]}

 BarChart[dalist, ChartStyle -> cogColors]

I don`t understand how to assign color to list and to value within the list.

Here my hope is to get each sublist ( first one being : {901, 503, 522, 1305}) assigned one color (Part[[]] of cogColors). Then each bar would be a darker/lighter but similar 开发者_开发百科color. Below is the desired output (ppt) :

BarChart[dalist, ChartStyle -> {cogColors, Opacity /@ {0.4, 0.6, 0.8, 1}}]

The crux lies in the following sentence in the doc page of ChartStyle:

With the form ChartStyle->{spec_1, spec_2, ...}, the i, j, ... element in a nested list of datasets has a style given by applying spec_1[[i]], then spec_2[[j]], etc.

This means you have to find directives that have cumulative effects. The combination of Opacity and colors has this. If you combine various colors you end up with the last one.

BarChart[MapThread[
  Style, {dalist, 
   Transpose@
    Reverse@NestList[Lighter, {Red, Green, Blue, Yellow}, 3]}, 2]]

Edit by Verbeia

You can use Blend and this approach of MapThread and Style to get whatever color combinations you want, eg:

extColours = 
 Outer[Blend[{#1, GrayLevel[0.1]}, #2] &, cogColors, {0.2, 0.4, 0.6, 0.8}];

BarChart[MapThread[Style, {dalist, extColours}, 2]]