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I have data of letter occurrences in different positions. I want to plot the frequency of each letter in each position.

The type of plot I have in mind is as follows:

sample image

How can I do this in Mathematica?

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    $\begingroup$ What have you tried? Take a look at the documentation for BarChart: there is a ChartLayout called "Stacked"... Have you searched this site? Quite a few results pop up for "stacked barchart". $\endgroup$ – MarcoB Sep 10 '15 at 16:24
  • $\begingroup$ I think both BarChart and Histogram support this type of data visualization. $\endgroup$ – march Sep 10 '15 at 16:24
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    $\begingroup$ Table[BarChart[RandomReal[1, {5, 5}], ChartLayout -> l], {l, {"Stacked", "Percentile"}}] $\endgroup$ – Dr. belisarius Sep 10 '15 at 16:25
  • $\begingroup$ @belisarius Thanks. I did not find the option "Percentile" (which is what I want) in the Options section of the documentation, under ChartLayout, where I would expect to find it. Can you post an answer so I can accept it? $\endgroup$ – becko Sep 10 '15 at 16:30
  • $\begingroup$ @MarcoB Stacked is not what I want. Percentile is more like it, but that's not in the documentation. $\endgroup$ – becko Sep 10 '15 at 16:31
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This does what you want:

BarChart[RandomReal[1, {5, 5}], ChartLayout -> "Percentile"]

Mathematica graphics

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A bit more detail than in belisarius' answer:

BarChart[RandomReal[1, {21, 26}], 
 ChartLayout -> "Percentile", 
 ChartLegends -> RandomSample[CharacterRange["A", "Z"], 26], 
 ChartLabels -> {Rotate[#, 90 Degree] & /@ Range[105, 125], None}, 
 ChartStyle -> ColorData[54], 
 AxesLabel -> {Placed[
    Text[Style["aa position", 14, Bold, 
      FontFamily -> Helvetica]], {13, -12}], 
    Text[Style["Frequency", 14, Bold, FontFamily -> Helvetica]]}, 
 PlotLabel -> Text[Style["Young", 16, Bold, FontFamily -> Helvetica]],
 ImageSize -> 700]

enter image description here

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I've been reading a few books on visualisation theory recently and wanted to add my two English pennies - the ordering of data in stacked bar charts matters. Particularly the variance of the lower elements.

To demonstrate this, here's a function that re-orders data according to the Variance or Mean of the datasets (EDIT: Changed to Transpose on Belisarius' recommendation and used https://mathematica.stackexchange.com/a/2810/1952 for code formatting):

sortedStackedBarChart[data_List, "Sorting" -> method_, 
  "StackLayout" -> stacking_, opts : OptionsPattern[]] :=
With[{orderedData = Switch[method,
     "Variance",
     data[[All, Ordering[Variance /@ Transpose[data]]]],
     "Mean",
     data[[All, Reverse[Ordering[Mean /@ Transpose[data]]]]]
     ]},
  BarChart[orderedData, ChartLayout -> stacking, 
   FilterRules[{opts}, Options[BarChart]]]]

Generate some data, of course I've selected some of my datasets to have lower variances than others:

SeedRandom[1111987]; allRandomData = 
 Table[{RandomReal[{1.9, 2.1}], RandomReal[{0.5, 1}], 
   RandomReal[{0.2, 6}], RandomReal[{0.2, 4}], 
   RandomReal[{4, 5}]}, {10}];

Comparing the "Mean" stack ordering and "Variance" stack ordering, it's easier to understand the relative differences between each stack with Variance ordering:

Grid[{{sortedStackedBarChart[allRandomData, "Sorting" -> "Mean", 
    "StackLayout" -> "Percentile", ImageSize -> 300], 
   sortedStackedBarChart[allRandomData, "Sorting" -> "Mean", 
    "StackLayout" -> "Stacked", ImageSize -> 300]}}]

enter image description here

Grid[{{sortedStackedBarChart[allRandomData, "Sorting" -> "Variance", 
    "StackLayout" -> "Percentile", ImageSize -> 300], 
   sortedStackedBarChart[allRandomData, "Sorting" -> "Variance", 
    "StackLayout" -> "Stacked", ImageSize -> 300]}}]

enter image description here

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  • $\begingroup$ really impressive +1 $\endgroup$ – Dr. belisarius Sep 11 '15 at 11:54
  • $\begingroup$ Instead of Table[Variance[data[[All, i]]], {i, dims[[2]]}] you can use Variance /@ Transpose@data. The same with Mean $\endgroup$ – Dr. belisarius Sep 11 '15 at 12:14
  • $\begingroup$ @belisarius eurgh, how embarrassing. Thanks for suggestion, allows the removal of the Module[{..},With[...]] mess. Cheers $\endgroup$ – Martin John Hadley Sep 11 '15 at 13:04
  • $\begingroup$ Glad to help :) $\endgroup$ – Dr. belisarius Sep 11 '15 at 13:20

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