matlab 画图时部分问题以及解决方法

最近在使用 matlab 画图时，遇到了许许多多各式各样的问题，有些问题甚至折腾了很久才搞好，特此记录下来。

1. 设置画图时图中线段的粗细

plot(x1,y1,'b-','LineWidth',2);

2. 设置x轴y轴的范围

axis([0,3000,0,100]);

3. 多张图在一个页面中绘出

% 绘完每张图后在使用 hold on,并在最后使用 hold off
plot(x1,y1,'b-','LineWidth',2);
hold on;
plot(x2,y2,'r:','LineWidth',2);
hold off;

4. 设置图例的位置

详见官方文档：https://ww2.mathworks.cn/help/releases/R2016b/matlab/ref/legend.html?searchHighlight=legend&s_tid=doc_srchtitle#zmw57dd0e451323

% Location 表示相对于坐标的位置，northwest 表示 左上
legend('location', 'northwest');

5. 去除图中上方与右方的的边框

  • 方法一：在绘图操作（plot）之前添加 hold on; 即可
    hold on;
plot(x1,y1,'b-','LineWidth',2);
  • 方法二：在绘图操作（plot）之后添加 box off; 即可
    plot(x1,y1,'b-','LineWidth',2);
box off;

6. 设置 X 轴标签为中文

set(gca,'XTickLabel',{'第一个','第二个','第三个'});

7. 为柱状图进行形状填充

使用自封装函数 applyhatch.m，相关链接：https://www.ilovematlab.cn/thread-177581-1-1.html

  • 首先新建函数脚本applyhatch.m

    % applyhatch.m

function applyhatch(h,patterns,colorlist)
% APPLYHATCHApply hatched patterns to a figure
% APPLYHATCH(H,PATTERNS) creates a new figure from the figure H by
% replacing distinct colors in H with the black and white
% patterns in PATTERNS. The format for PATTERNS can be
%   a string of the characters '/', '\', '|', '-', '+', 'x', '.'
%   a cell array of matrices of zeros (white) and ones (black)
%
% APPLYHATCH(H,PATTERNS,COLORS) maps the colors in the n by 3
% matrix COLORS to PATTERNS. Each row of COLORS specifies an RGB
% color value.
%
% Note this function makes a bitmap image of H and so is limited
% to low-resolution, bitmap output.
%
% Example 1:
%   bar(rand(3,4));
%   applyhatch(gcf,'\-x.');
%
% Example 2:
%   colormap(cool(6));
%   pie(rand(6,1));
%   legend('Jan','Feb','Mar','Apr','May','Jun');
%   applyhatch(gcf,'|-+.\/',cool(6));
%
% See also: MAKEHATCH
% By Ben Hinkle, 
% This code is in the public domain. 

oldppmode= get(h,'paperpositionmode');
oldunits= get(h,'units');
set(h,'paperpositionmode','auto');
set(h,'units','pixels');
figsize= get(h,'position');
if nargin == 2
colorlist = [];
end
bits= hardcopy(h,'-dzbuffer','-r0');
set(h,'paperpositionmode',oldppmode);
bwidth= size(bits,2);
bheight= size(bits,1);
bsize= bwidth * bheight;
if~isempty(colorlist)
    colorlist = uint8(255*colorlist);
    [colors,colori] = nextnonbw(0,colorlist,bits);
else
    colors = (bits(:,:,1) ~= bits(:,:,2)) | ...
        (bits(:,:,1) ~= bits(:,:,3));
end
pati= 1;
colorind= find(colors);
while~isempty(colorind)
    colorval(1) = bits(colorind(1));
    colorval(2) = bits(colorind(1)+bsize);
    colorval(3) = bits(colorind(1)+2*bsize);
    if iscell(patterns)
        pattern = patterns{pati};
    elseif isa(patterns,'char')
        pattern = makehatch(patterns(pati));
    else
        pattern = patterns;
    end
    pattern = uint8(255*(1-pattern));
    pheight = size(pattern,2);
    pwidth = size(pattern,1);
    ratioh = ceil(bheight/pheight);
    ratiow = ceil(bwidth/pwidth);
    bigpattern = repmat(pattern,[ratioh ratiow]);
    if ratioh*pheight > bheight
        bigpattern(bheight+1:end,:) = [];
    end
    if ratiow*pwidth > bwidth
        bigpattern(:,bwidth+1:end) = [];
    end
    bigpattern = repmat(bigpattern,[1 1 3]);
    color = (bits(:,:,1) == colorval(1)) & ...
        (bits(:,:,2) == colorval(2)) & ...
        (bits(:,:,3) == colorval(3));
    color = repmat(color,[1 1 3]);
    bits(color) = bigpattern(color);
    if ~isempty(colorlist)
        [colors,colori] = nextnonbw(colori,colorlist,bits);
    else
        colors = (bits(:,:,1) ~= bits(:,:,2)) | ...
            (bits(:,:,1) ~= bits(:,:,3));
    end
    colorind = find(colors);
    pati = (pati + 1);
    if pati > length(patterns)
        pati = 1;
    end
end
newfig= figure('units','pixels','visible','off');
imaxes= axes('parent',newfig,'units','pixels');
im= image(bits,'parent',imaxes);
fpos= get(newfig,'position');
set(newfig,'position',[fpos(1:2) figsize(3) figsize(4)+1]);
set(imaxes,'position',[0 0 figsize(3) figsize(4)+1],'visible','off');
set(newfig,'visible','on');


function [colors,out] = nextnonbw(ind,colorlist,bits)
out = ind+1;
colors = [];
while out <= size(colorlist,1)
if isequal(colorlist(out,:),[255 255 255]) | ...
        isequal(colorlist(out,:),[0 0 0])
    out = out+1;
else
    colors = (colorlist(out,1) == bits(:,:,1)) & ...
            (colorlist(out,2) == bits(:,:,2)) & ...
            (colorlist(out,3) == bits(:,:,3));
    return
end
end

% 而applyhatch函数需要调用下面的函数

function A = makehatch(hatch)
%MAKEHATCH Predefined hatch patterns
%  MAKEHATCH(HATCH) returns a matrix with the hatch pattern for HATCH
%   according to the following table:
%      HATCH        pattern
%     -------      ---------
%        /          right-slanted lines
%        \          left-slanted lines
%        |          vertical lines
%        -          horizontal lines
%        +          crossing vertical and horizontal lines
%        x          criss-crossing lines
%        .          single dots
%
%  See also: APPLYHATCH

%  By Ben Hinkle,
%  This code is in the public domain.

n = 6;
A=zeros(n);
switch (hatch)
case '/'
A = fliplr(eye(n));
case '\'
A = eye(n);
case '|'
A(:,1) = 1;
case '-'
A(1,:) = 1;
case '+'
A(:,1) = 1;
A(1,:) = 1;
case 'x'
A = eye(n) | fliplr(diag(ones(n-1,1),-1));
case '.'
A(1:2,1:2)=1;
otherwise
error(['Undefined hatch pattern "' hatch '".']);
end

  • 第二部在需要的地方调用函数

    %为柱状图进行形状填充，\.x- 为填充类型，可继续往后添加，详见 applyhatch.m 源码
bar(y);
applyhatch(gcf,'\.x-');

8. 当坐标轴数字太大时，设置坐标轴不用科学计数法表示

%设置柱状图 y 坐标不用科学计数法表示
y_val=get(gca,'YTick');   %为了获得y轴句柄
y_str=num2str(y_val');    %为了将数字转换为字符数组
set(gca,'YTickLabel',y_str);    %显示

9. 在柱状图上方显示数据

%使用 text(xt,yt,str_num) 函数，xt,yt 表示坐标，str_num 表示 str 类型的数据

y=[10,20,30,40];
xy=bar(y,0.5);
axis([0,5,1,50]);
%去除上边和右边的边框
box off;
%设置柱状图上方数据
for i = 1:4
    text(i-0.15,y(i)+2,num2str(y(i)));
end
matlab画图时遇到的一些问题-202111616835.png