【可视化】基于Matlab实现图表视化相关矩阵，相关值显示为左下角的热图，使用颜色渐变来指示强度,福利

本文介绍了如何在Matlab中利用corr函数生成相关矩阵，并通过heatmap函数创建热图以直观展示数据间的关系。通过色彩渐变，可以快速发现数据的相关性。此外，文章还提及了Matlab在其他领域的应用，如机器学习、图像处理、路径规划等。

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🔥 内容介绍

在数据分析和可视化中，图表视化是一种非常有用的工具。通过图表视化，我们可以更直观地理解数据之间的关系和趋势。在Matlab中，我们可以通过简单的代码实现图表视化，并且可以使用颜色渐变来显示相关值的强度。

在本文中，我们将介绍如何使用Matlab实现图表视化相关矩阵，并将相关值显示为左下角的热图。首先，让我们来看看如何生成相关矩阵。在Matlab中，我们可以使用corr函数来计算相关矩阵。例如，我们可以使用以下代码生成一个随机的相关矩阵：

data = randn(100, 3); % 生成随机数据 corrMatrix = corr(data); % 计算相关矩阵

一旦我们有了相关矩阵，我们就可以使用图表视化来展示相关值的强度。我们可以使用热图来显示相关值，其中颜色的深浅表示相关值的强度。在Matlab中，我们可以使用heatmap函数来实现热图的可视化。以下是一个简单的示例代码：

heatmap(corrMatrix, 'Colormap', 'jet', 'ColorLimits', [-1, 1]); % 使用jet颜色映射，并设置颜色范围为-1到1

通过这段代码，我们可以将相关矩阵可视化为一个热图，并且使用颜色渐变来指示相关值的强度。这样，我们可以更直观地理解数据之间的关系，并且可以快速发现相关性较强的数据。

除了热图之外，Matlab还提供了许多其他图表视化的工具，如散点图、折线图、柱状图等。通过这些工具，我们可以更全面地分析和理解数据，为我们的工作和决策提供更多的参考和支持。

总之，图表视化是数据分析中非常重要的一环，通过Matlab，我们可以轻松实现相关矩阵的图表视化，并使用颜色渐变来指示相关值的强度。希望本文对你有所帮助，谢谢阅读！

📣 完整代码

function [ defaultColors ] = getdefaultcolors(n)    if(nargin < 1)       n = 0;     end    defaultColors = [0 0.447 0.741; 0.85 0.325 0.098; ...        0.929 0.694 0.125; 0.466 0.674 0.188; 0.301 0.745 0.933; ...        0.494 0.184 0.556; 0.635 0.078 0.184];        other_colors = [0         0.3793    0.1379;                    1.0000    0.0345    0.6897;                    0.1034    1.0000         0;                    0         0.2069    0.1724;                    0.5172    0.1724    1.0000;                    0.9310    1.0000         0;                    0.2069    0.1724    0.1724;                    0         0.1034    0.3448;                    0.7931         0    0.3448;                    1.0000    0.1034    0.9310];     defaultColors = [defaultColors; other_colors];    if(n > size(defaultColors, 2))        clr = distinguishable_colors(n - size(defaultColors, 1), [defaultColors; 0 0 0; 1 1 1], @(x) colorspace('RGB->HSV',x));        defaultColors = [defaultColors; clr];    endend

function[width, height] = measureText(txt, opt, axis)    if(nargin < 3)       axis = gca();     end    hTest = text(axis, 0, 0, txt, opt);    textExt = get(hTest, 'Extent');    delete(hTest);    height = textExt(4);    %Height    width = textExt(3);     %Widthend

%% Prepare the data% Load the example dataset and compute correlation matrixD = load('patients.mat');D.IsFemale = ismember(D.Gender, 'Female');[~, D.HealthStatus] = ismember(D.SelfAssessedHealthStatus, {'Poor', 'Fair', 'Good', 'Excellent'});% Prepare the matrixX = [D.IsFemale, D.Age, D.Weight, D.Height, D.Smoker, ...     D.Systolic, D.Diastolic, D.HealthStatus];axislabels = {'GenderFemale', 'Age', 'Weight', 'Height', ...    'IsSmoker', 'Systolic', 'Diastolic', 'HealthStatus'};C = corr(X);%% Draw the correlogram% Prepare the figure and set the sizefigure(1); clf();set(gcf, 'Position', [0 0 640 480]); movegui('center');% Draw the figurecorrelogram(C, 'AxisLabels', axislabels); set(gca, 'FontSize', 12)

function [] = correlogram(C, varargin)    warning('off', 'MATLAB:polyshape:repairedBySimplify');    p = inputParser;    validX = @(x) validateattributes(x, {'cell', 'numeric', 'logical'}, ...        {'2d', 'nonempty', 'real', '<=', 1, '>=', -1});    validScalar = @(x) validateattributes(x, {'logical', 'numeric'}, ...        {'scalar','nonempty','real','nonnan'});    validColorArray = @(x) validateattributes(x, {'numeric'}, ...        {'2d', 'nonempty', 'real', 'nonnan', 'ncols', 3});    addRequired(p, 'C', validX);    addParameter(p, 'AxisLabels', [], @iscell);    addParameter(p, 'Labels', [], @iscell);    addParameter(p, 'cMin', -1, validScalar);    addParameter(p, 'cMax', 1, validScalar);    addParameter(p, 'colorMin', [0 0 1], validColorArray);    addParameter(p, 'colorZero', [1 1 1]*0.96, validColorArray);    addParameter(p, 'colorMax', [1 0 0], validColorArray);    addParameter(p, 'numDigits', 2, @isnumeric);    addParameter(p, 'boxWidthRatio', 1, validScalar);    addParameter(p, 'boxHeightRatio', 1, validScalar);    addParameter(p, 'BoxLineWidth', 0.5, validScalar);    addParameter(p, 'RadiusRatio', 0.9, validScalar);    addParameter(p, 'Colors', [], @isnumeric);    addParameter(p, 'VariableNames', cell(length(C), 1), @iscell);    addParameter(p, 'ShowDiagonal', false, @islogical);    addParameter(p, 'FontSize', [], validScalar);    addParameter(p, 'Sorting', true, @islogical);    addParameter(p, 'XDir', 'normal', @ischar);    addParameter(p, 'YDir', 'reverse', @ischar);    parse(p, C, varargin{:});    param = p.Results;    checkUsingDefaults = @(p,varname) any(strcmp(p.UsingDefaults,varname));    [nRow, nColumn] = size(C);    if((nRow == nColumn) && param.Sorting)         for i = 1:2            Z = linkage(C, 'average');            D = pdist(C);            si = optimalleaforder(Z, D);            C = C(si, si);            if(~isempty(param.AxisLabels))                param.AxisLabels = param.AxisLabels(si);                param.VariableNames = param.VariableNames(si);            end        end    end        if(checkUsingDefaults(p, 'Labels'))        labels = cell(size(C));        for iRow = 1:nRow            for iColumn = 1:nColumn                cValue = C(iRow, iColumn);                labels{iRow, iColumn} = num2str(cValue, ['%.', num2str(param.numDigits), 'f']);                if(iRow == iColumn); labels{iRow, iColumn} = param.VariableNames{iRow}; end            end        end        param.Labels = labels;    end       if(checkUsingDefaults(p, 'Colors'))        colorMin = param.colorMin;        colorZero = param.colorZero;        colorMax = param.colorMax;        cols = color_spacing_continuous(C(:), [param.cMin; 0; param.cMax], [colorMin; colorZero; colorMax]);        param.Colors = reshape(cols, nRow, nColumn, 3);    end        box_width_ratio = param.boxWidthRatio;    box_height_ratio = param.boxHeightRatio;        row_height = 1 ./ nRow;    col_width = 1./ nColumn;        xcPos = zeros(nColumn, 1);    ycPos = zeros(nRow, 1);        for iRow = 1:nRow        for iColumn = 1:nColumn            row_gap = (1 - box_height_ratio) * 0.5;            col_gap = (1 - box_width_ratio) * 0.5;            x = 0 + (col_gap + iColumn - 1) * col_width;            y = 0 + (row_gap + iRow - 1) * row_height;            w = col_width * (1 - col_gap);            h = row_height * (1 - row_gap);            xcenter = x + w/2;            ycenter = y + h/2;            xcPos(iColumn) = xcenter;            ycPos(iRow) = ycenter;        end    end    isHoldOn = ishold();    if(~isHoldOn)        cla();    end    hold('on');    set(gca, 'XTick', xcPos, 'XTickLabel', param.AxisLabels);    set(gca, 'YTick', ycPos, 'YTickLabel', param.AxisLabels);    xlim([0 1]);    ylim([0 1]);    dim1 = get(gcf, 'Position');    dim2 = get(gca, 'Position');    axis_width = dim1(3) * dim2(3);    axis_height = dim1(4) * dim2(4);    width_to_height = axis_width / axis_height;    alpha = 0.8;    if(width_to_height >= 1)        r_width_mult = 1 / (width_to_height^alpha);        r_height_mult = 1;    else        r_width_mult = 1;        r_height_mult = (width_to_height^alpha);    end    S = struct();    S.FontSize = 10;    [txt_width, txt_height] = measureText('-0.99', S, gca);    scaling = max(txt_width / col_width, txt_height / row_height);    desired_txt_gap = 0.9;    font_size = max(floor(S.FontSize * (1/scaling) * desired_txt_gap), 1);    if(isempty(param.FontSize))        param.FontSize = font_size;    end    txtOptions = struct();    txtOptions.HorizontalAlignment = 'center';    txtOptions.VerticalAlignment = 'middle';    txtOptions.FontSize = param.FontSize;        rec_line_width = param.BoxLineWidth;    for iRow = 1:nRow        for iColumn = 1:nColumn            row_gap = (1 - box_height_ratio) * 0.5;            col_gap = (1 - box_width_ratio) * 0.5;            x = 0 + (col_gap + iColumn - 1) * col_width;            y = 0 + (row_gap + iRow - 1) * row_height;            w = col_width * (1 - col_gap);            h = row_height * (1 - row_gap);            xcenter = x + w/2;            ycenter = y + h/2;            xcPos(iColumn) = xcenter;            ycPos(iRow) = ycenter;            pos = [x y w h];            color = param.Colors(iRow, iColumn, :);                        if(iRow > iColumn)                rectangle('Position',pos, 'FaceColor', color, 'LineWidth', rec_line_width)                txt = param.Labels{iRow, iColumn};                text(xcenter, ycenter, txt, txtOptions);            end            if((iRow == iColumn) && param.ShowDiagonal)                rectangle('Position',pos, 'FaceColor', color, 'LineWidth', rec_line_width)                txt = param.Labels{iRow, iColumn};                text(xcenter, ycenter, txt, txtOptions);            end            if(iRow < iColumn)                cvalue = C(iRow, iColumn);                theta_start = -0.5 * pi;                theta_end = theta_start + (cvalue * 2 * pi);                theta_range = theta_end - theta_start;                                n = 100;                ww = w * param.RadiusRatio * r_width_mult;                hh = h * param.RadiusRatio * r_height_mult;                                theta = [(0:n-1)]*(2*pi)/n;                xx = xcenter + [0.5*ww*cos(theta)];                yy = ycenter + [0.5*hh*sin(theta)];                Pcircle = polyshape(xx,yy);                theta = [(0:n-1) (n-1e-3)]*(theta_range)/n + theta_start;                xx = xcenter + [0 0.5*ww*cos(theta)];                yy = ycenter + [0 0.5*hh*sin(theta)];                P = polyshape(xx,yy);                                plot(Pcircle, 'FaceAlpha', 0, 'LineStyle', '-', 'EdgeColor', [1 1 1] * 0.55);                plot(P, 'FaceAlpha', 1, 'FaceColor', color);            end                    end    end    set(gca, 'XDir', param.XDir);    set(gca, 'YDir', param.YDir)    if(~isHoldOn); hold('off'); endend

function [C] = color_spacing_continuous( values, breaks, colors)    indices = zeros(size(values));    for i = 1:length(breaks)       if(i ~= length(breaks))           q = values >= breaks(i);       else           q = values > breaks(i);       end       indices(q) = indices(q) + 1;    end    ratio = zeros(size(values));    ranges = breaks(2:end) - breaks(1:(end)-1);    for i = 1:(length(breaks)-1)        ind = indices == i;        ratio(ind) = (values(ind) - breaks(i)) / (ranges(i));            end    C = (1-ratio).*colors(indices, :) + ratio.*colors(indices+1, :);end