(*
    Independent Component Analysis Mathematica package
    Copyright (C) 2016  Anton Antonov

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.

	  Written by Anton Antonov,
	  antononcube @ gmail.com,
	  Windermere, Florida, USA.
*)

(*
    Mathematica is (C) Copyright 1988-2016 Wolfram Research, Inc.

    Protected by copyright law and international treaties.

    Unauthorized reproduction or distribution subject to severe civil
    and criminal penalties.

    Mathematica is a registered trademark of Wolfram Research, Inc.
*)

(* :Title: IndependentComponentAnalysis *)
(* :Context: IndependentComponentAnalysis` *)
(* :Author: Anton Antonov *)
(* :Date: 2016-05-14 *)

(* :Package Version: 0.8 *)
(* :Mathematica Version: 10.4.1 *)
(* :Copyright: (c) 2016 Anton Antonov *)
(* :Keywords: Independent Component Analysis, ICA, FastICA, matrix factorization *)
(* :Discussion: *)

(* Version 0.8 *)
(*

    This package provides functions for performing Independent Component Analysis (ICA) over matrices.
    The function IndependentComponentAnalysis is intended to be the front of different algorithms for ICA.

    ICA can be seen as a dimension reduction or matrix factorization technique. Because of that the function
    IndependentComponentAnalysis returns a pair of matrices the product of which should approximate the first
    argument. This is different from the result of R's FastICA. Because of this a separate function, FastICA,
    is provided.

    The first version of this package implements the algorithm FastICA.
    The implementation follows closely the code in the R library FastICA.R, see

      https://cran.r-project.org/web/packages/fastICA/index.html ,

    and the article

      A. Hyvarinen and E. Oja (2000) Independent Component Analysis: Algorithms and Applications,
      Neural Networks, 13(4-5):411-430 .

    *********************
    Usage example
    **********************

    In the code below the columns of S have the independent components, the rows are samples.
    The matrix A provides linear mixing. The matrix M has the mixed signals.
    The independent component analysis functions should be fairly fast.

    (* Signal functions *)
    Clear[s1, s2, s3]
    s1[t_] := Sin[600 \[Pi] t/10000 + 6*Cos[120 \[Pi] t/10000]] + 1.2
    s2[t_] := Sin[\[Pi] t/10] + 1.2
    s3[t_?NumericQ] := (((QuotientRemainder[t, 23][[2]] - 11)/9)^5 + 2.8)/2 + 0.2

    (* Mixing matrix *)
    A = {{0.44, 0.2, 0.31}, {0.45, 0.8, 0.23}, {0.12, 0.32, 0.71}};

    (* Signals matrix *)
    nSize = 600;
    S = Table[{s1[t], s2[t], s3[t]}, {t, 0, nSize, 0.5}];
    Dimensions[S]
    (* {1201, 3} *)

    (* Mixed signals matrix *)
    M = S.A;
    Grid[{Map[ListLinePlot[#, PlotRange -> All, ImageSize -> 250] &, Transpose@S]}]

    (* Mixed signals *)
    Grid[{Map[ListLinePlot[#, PlotRange -> All, ImageSize -> 250] &, Transpose@M]}]

    (* ICA function call *)
    AbsoluteTiming[
      res = IndependentComponentAnalysis[M, 3];
    ]
    (* {0.010782, Null} *)

    (* Approximation norm *)
    Norm[M - Dot @@ res]
    (* 5.25579*10^-14 *)

    (* Visualize the source signals result *)
    ListLinePlot[#, ImageSize -> Medium] & /@ Transpose[res[[1]]]


TODO:
    1. Implement symmetric FastICA using logcosh/exp/etc approx. to neg-entropy function.
    2. Implement NNMF based method for ICA.
    3. Handling high precision matrices.

    This file was created by Mathematica Plugin for IntelliJ IDEA.
*)

BeginPackage["IndependentComponentAnalysis`"];


IndependentComponentAnalysis::usage = "IndependentComponentsAnalysis[ X_?MatrixQ, k_Integer ] \
independent components analysis (factorization) over the matrix X for k number of components.";

FastICA::usage = "FastICA[X_?MatrixQ, k_Integer, opts___] applies the algorithm FastICA to X in order to find \
k independent components. Returns an association with the corresponding matrix names as keys.";

Begin["`Private`"];

Clear[IndependentComponentAnalysis, FastICA];

IndependentComponentAnalysis::nomat = "A matrix is expected as a first argument.";
IndependentComponentAnalysis::noint = "A positive integer no greater than the number of columns of the matrix \
is expected as a second argument.";
IndependentComponentAnalysis::nometh = "Unknown method.";

FastICA::nomat = "A matrix is expected as a first argument.";
FastICA::noint = "A positive integer no greater than the number of columns of the matrix \
is expected as a second argument.";
FastICA::unmat = "The un-mixing matrix option value should be Automatic or a square matrix corresponding \
to the number of components.";

Options[IndependentComponentAnalysis] = { Method -> "FastICA", MaxSteps -> 200, PrecisionGoal -> 6 };

IndependentComponentAnalysis[ X_, k_, opts : OptionsPattern[] ] :=
    Block[{method, maxSteps, pgoal, mopts, res},

      If[ !MatrixQ[X],
        Message[IndependentComponentAnalysis::nomat];
        Return[$Failed]
      ];

      If[ !IntegerQ[k] || !( 1 <= k <= Dimensions[X][[2]] ),
        Message[IndependentComponentAnalysis::noint];
        Return[$Failed]
      ];

      method = OptionValue[IndependentComponentAnalysis, Method];
      maxSteps = OptionValue[IndependentComponentAnalysis, MaxSteps];
      pgoal = OptionValue[IndependentComponentAnalysis, PrecisionGoal];

      If[ method == "FastICA" || ( ListQ[method] && method[[1]] == "FastICA" ),
        If[ ListQ[method], mopts = DeleteCases[method, "FastICA"], mopts = {} ];
        mopts = Join[mopts, {MaxSteps->maxSteps, PrecisionGoal->pgoal}];
        res = FastICA[ X, k, "RFastICAResult" -> False, Sequence @@ mopts ];
        If[AssociationQ[res], {res["S"], res["A"]}, res],
        (* ELSE *)
        Message[ IndependentComponentAnalysis::nometh ];
        $Failed
      ]

    ];


Options[FastICA] =
    {"NonGaussianityFunction" -> Automatic, "NegEntropyFactor" -> 1, "InitialUnmixingMartix" -> Automatic,
      "RowNorm" -> False, MaxSteps -> 200, PrecisionGoal -> 6, "RFastICAResult" -> True };

FastICA[ X_?MatrixQ, k_Integer, opts : OptionsPattern[] ] :=
    Block[{nonGaussFunc, alpha, rowNormQ, unmixMatSpec, maxSteps, pgoal,
      n, m, ncomp = k, wInitMat, V, XU, XD, XV, XD1, K, X1, W, aMat, wMat, S, A },

      nonGaussFunc = OptionValue[FastICA, "NonGaussianityFunction"];
      alpha = OptionValue[FastICA, "NegEntropyFactor"];
      rowNormQ = OptionValue[FastICA, "RowNorm"];
      unmixMatSpec = OptionValue[FastICA, "InitialUnmixingMartix"];
      maxSteps = OptionValue[FastICA, MaxSteps];
      pgoal = OptionValue[FastICA, PrecisionGoal];

      If[ !MatrixQ[X],
        Message[FastICA::nomat];
        Return[$Failed]
      ];

      If[ !IntegerQ[ncomp] || k > Dimensions[X][[2]],
        Message[FastICA::noint];
        Return[$Failed]
      ];

      If[ TrueQ[nonGaussFunc===Automatic],
        nonGaussFunc = Log[Cosh[#]]&;
      ];

      Which[
        TrueQ[unmixMatSpec===Automatic],
        wInitMat =
            Partition[RandomVariate[NormalDistribution[], ncomp^2], ncomp],
        TrueQ[ MatrixQ[unmixMatSpec] && Dimensions[unmixMatSpec] == {ncomp,ncomp}],
        wInitMat = unmixMatSpec,
        True,
        Message[FastICA::unmat];
        Return[$Failed]
      ];

      {n, m} = Dimensions[X];

      (* Centering *)

      If[rowNormQ,
        X1 = Standardize[#, Mean, StandardDeviation] & /@ Transpose[X],
        X1 = Standardize[#, Mean, 1 &] & /@ Transpose[X]
      ];

      If[ TrueQ[ Head[X]===SparseArray ], X1 = SparseArray[X1] ];

      (*Whitening*)

      V = X1.Transpose[X1]/n;
      {XU, XD, XV} = SingularValueDecomposition[V];

      XD1 = DiagonalMatrix[ 1/Sqrt[Map[If[# < 10^-12, 1, #] &, Diagonal[XD]]]];

      K = XD1.Transpose[XU];
      K = K[[1 ;; ncomp, All]];

      If[ TrueQ[ Head[X]===SparseArray ], K = SparseArray[K] ];

      (*X1 = K.X1;*)

      aMat = ICADeflation[ K.X1, ncomp, wInitMat, nonGaussFunc, pgoal, alpha, maxSteps];

      If[ TrueQ[ Head[X]===SparseArray ], aMat = SparseArray[aMat] ];

      (*wMat = aMat . K;*)
      (*S = wMat . Transpose[X];*)
      (*A = Transpose[wMat] . Inverse[ wMat . Transpose[wMat] ] ;*)
      (*AssociationThread[ {"K","W","A","S"}->Transpose /@ { K, aMat, A, S} ]*)

      (* return(list(X = t(X), K = t(K), W = t(a), A = t(A), S = t(S))) *)

      K = Transpose[K];
      aMat = Transpose[aMat];
      X1 = Transpose[X1];

      wMat = K . aMat;
      A = Transpose[wMat.Inverse[Transpose[wMat].wMat]];

      (*Print["Head/@{X1, K, aMat, wMat, A, S}] :", Head/@{X1, K, aMat, wMat, A, S} ];*)

      (*If[ TrueQ[ Head[X]===SparseArray ], A = SparseArray[A] ];*)

      If[ OptionValue[FastICA, "RFastICAResult"],

        S = X1 . wMat;

        AssociationThread[ {"X","K","W","A","S"}-> { X1, K, aMat, A, S} ],
        (*ELSE*)

        S = X . wMat;

        AssociationThread[ {"K","W","A","S"}-> { K, aMat, A, S} ]
      ]
    ];


Clear[ICADeflation];
ICADeflation[ X_?MatrixQ, ncomp_Integer, wInitMat_?MatrixQ, func_, pgoal_?NumberQ, alpha_?NumberQ, maxSteps_Integer ] :=
    Block[{n, m, w, w1, W, g, gp, t, k, nStep=0,
           wx, gwx, gwxMat, xgwxMat, gpwx, v1, v2, wd },
      {n,m} = Dimensions[ X ];
      g = func';
      gp = func'';

      W = ConstantArray[0,{ncomp,ncomp}];

      Do[
        w = wInitMat[[i,All]];

        If[ i > 1,

          t = ConstantArray[0,Length[w]];

          Do[
            k = w . W[[j,All]];
            t = t + k * W[[j,All]];
          , {j,1,i-1}];

          w = w - t;
        ];

        w = w / Norm[w];

        wd = 1000;
        While[ wd > 10^-pgoal && nStep < maxSteps,
          nStep ++;

          wx = w.X;

          gwx = g[alpha*wx];
          gwxMat = Table[gwx, {ncomp}];

          xgwxMat = X*gwxMat;

          v1 = Mean /@ xgwxMat;

          gpwx = alpha*g[alpha*wx];

          v2 = Mean[gpwx]*w;

          w1 = v1 - v2;

          If[ i > 1,

            t = ConstantArray[0,Length[w1]];

            Do[
              k = w1 . W[[j,All]];
              t = t + k * W[[j,All]];
              , {j,1,i-1}];

            w1 = w1 - t;
          ];

          w1 = w1 / Norm[w1];

          wd = Abs[ Abs[w.w1] - 1 ];

          w = w1;
        ]; (* While *)

        W[[i,All]] = w;

        ,{i,1,ncomp}]; (*Do*)

      W
    ];

End[]; (* `Private` *)

EndPackage[]