scatter3 三维散点图
% scatter3 用法类似scatter
x = linspace(0, 6*pi, 300);
y = sin(x);
z = cos(x);
scatter3(x, y, z, 'o', 'MarkerEdgeColor','b',"MarkerFaceColor",'r');
mesh、surf 三维曲面
meshgrid 用法
x = 1:3;
y = 1:5;
[X,Y] = meshgrid(x,y)
% 绘制 z = x*e^(-(x^2+y^2))
% mesh 绘制的是网格
[x,y] = meshgrid(-10:1:10, -10:1:10);
z = x.*exp(-x.^2-y.^2);
mesh(x,y,z);
% 绘制 z = x*e^(-(x^2+y^2))
% surf 绘制的是曲面
[x,y] = meshgrid(-10:1:10, -10:1:10);
z = x.*exp(-x.^2-y.^2);
surf(x,y,z);
MATLAB文件读写
将数据写入文件
% writetable(m, filename)：将m写入名为filename的文件
% 支持的文件扩展名：.txt .csv .xls .xlsm 或 .xlsx
m = rand(4) + 1;
m = round(m, 2, 'decimals'); % decimals：小数位数; significant：有效数字位数
t = table(m)
m
____________________________
1.51 1.38 1.94 1.59
1.82 1.81 1.88 1.21
1.79 1.53 1.55
1.3
1.64 1.35 1.62 1.47
writetable(t, 'm.txt',"Delimiter","\t","WriteVariableNames",false); % 相对路径，设置数据分隔方式为空格
% Delimiter（指定分隔符）：默认","、"\t"、";"、"|"
% WriteVariableNames：是否显示列名
writetable(t,'E:\Project\MATLABProject\process\m.txt'); % 绝对路径
writetable(t,'E:\Project\MATLABProject\process\m.csv');
writetable(t,'E:\Project\MATLABProject\process\m.xls');
writetable(t,'E:\Project\MATLABProject\process\m.xlsm');
writetable(t,'E:\Project\MATLABProject\process\m.xlsx');
type m.txt % 显示内容
1.51 1.38 1.94 1.59
1.82 1.81 1.88 1.21
1.79 1.53 1.55 1.3
1.64 1.35 1.62 1.47
% 将多个矩阵保存在同一个文件 "append"
t2 = table(eye(4))
Var1
________________
1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1
% writeMode（写入模式）:'overwrite'（覆盖，默认）、'append'追加
writetable(t2, 'm.txt',"Delimiter","\t","WriteVariableNames",false,"WriteMode","append");
type m.txt;
1.51 1.38 1.94 1.59
1.82 1.81 1.88 1.21
1.79 1.53 1.55 1.3
1.64 1.35 1.62 1.47
1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1
从文件读取数据
% t = readtable(filename) 从filename 文件中读取数据
% 支持的拓展名：.txt .csv .xls .xlsb .xlsm .xlsx .xltm .xltx
t = readtable("m.txt")
Var1 Var2 Var3 Var4
____ ____ ____ ____
1.51 1.38 1.94 1.59
1.82 1.81 1.88 1.21
1.79 1.53 1.55
1.3
1.64 1.35 1.62 1.47
1
0
0
0
0
1
0
0
0
0
1
0
0
0
0
1
% table转化成数组
m = table2array(t)
列 1 至 3
1.5100 1.3800 1.9400
1.8200 1.8100 1.8800
1.7900 1.5300 1.5500
1.6400 1.3500 1.6200
1.0000
0
0
0 1.0000
0
0
0 1.0000
0
0
0
列 4
1.5900
1.2100
1.3000
1.4700
0
0
0
1.0000
% 读取excel表单
t = readtable('E:\Project\MATLABProject\process\m.xls')
m_1
m_2
m_3
m_4
____ ____ ____ ____
1.51 1.38 1.94 1.59
1.82 1.81 1.88 1.21
1.79 1.53 1.55
1.3
1.64 1.35 1.62 1.47
% 通过名称获取excel表单
t_grade = readtable("student.xls","Sheet","grade") % 指定从student.xls的grade表单读取数据
Var1
ID
Chinese Math English
____________ ____ _______ ____ _______
{'zhangsan'} 1001
98
94
95
{'lisi' } 1002
94
99
98
{'wangwu' } 1003
95
95
97
% 通过顺序获取excel表单
t_grade = readtable("student.xls","Sheet",1) % 指定从student.xls的第一个表单读取数据
Var1
ID
Chinese Math English
____________ ____ _______ ____ _______
{'zhangsan'} 1001
98
94
95
{'lisi' } 1002
94
99
98
{'wangwu' } 1003
95
95
97
t_info = readtable("student.xls","Sheet",2)
Var1
ID
Height Weight
____________ ____ ______ ______
{'zhangsan'} 1001
126
54
{'lisi' } 1002
128
56
{'wangwu' } 1003
135
55
% 获取student.xls所有表单名称
sheets = sheetname("student.xls")
"grade"
"info"
% 获取表单个数
length(sheets)
ans = 2
% 指定单元格范围获取
readtable("student.xls","Range","B2:E4")
Var1 Var2 Var3 Var4
____ ____ ____ ____
1001
98
94
95
1002
94
99
98
1003
95
95
97
table的更多用法
% table的构造
Names = {'zhangsan';'lisi';'wangwu'};
ID = {1001;1002;1003};
Chinese = {98;94;95};
Math = {94;99;95};
English = {95;98;97};
table(Names,ID,Chinese,Math,English)
Names
ID
Chinese
Math
English
____________ ________ _______ ______ _______
{'zhangsan'} {[1001]} {[98]}
{[94]} {[95]}
{'lisi' } {[1002]} {[94]}
{[99]} {[98]}
{'wangwu' } {[1003]} {[95]}
{[95]} {[97]}
table(ID,Chinese,Math,English,'RowNames',Names)
ID
Chinese
Math
English
________ _______ ______ _______
zhangsan {[1001]} {[98]}
{[94]} {[95]}
lisi
{[1002]} {[94]}
{[99]} {[98]}
wangwu
{[1003]} {[95]}
{[95]} {[97]}
% 访问表格元素
% 1、通过索引（和矩阵一致）
t_grade(1,2)
t_grade(1,1:5) ;
t_grade(1,:); % 获取第一行所有列
t_grade(:,[1,3]) % 获取所有行和第1、3列；
% 2、通过列名获取
t_grade(:,"ID")
ID
____
1001
1002
1003
t_grade(:,{'Var1','Chinese'})
Var1
Chinese
____________ _______
{'zhangsan'}
98
{'lisi' }
94
{'wangwu' }
95
% 修改列名
t_grade.Properties.VariableNames
列 1 至 3
{'Var1'} {'ID'} {'Chinese'}
列 4 至 5
{'Math'} {'English'}
t_grade.Properties.VariableNames(1) = {'Name'}
Name
ID
Chinese Math English
____________ ____ _______ ____ _______
{'zhangsan'} 1001
98
94
95
{'lisi' } 1002
94
99
98
{'wangwu' } 1003
95
95
97
% 增加行
t_grade(4,:) = {'zhao',1004,98,95,100}
Name
ID
Chinese Math English
____________ ____ _______ ____ _______
{'zhangsan'} 1001
98
94
95
{'lisi' } 1002
94
99
98
{'wangwu' } 1003
95
95
97
{'zhao' } 1004
98
95
100
% 增加列
t_grade.total = t_grade.Chinese + t_grade.Math + t_grade.English
Name
ID
Chinese Math English total
____________ ____ _______ ____ _______ _____
{'zhangsan'} 1001
98
94
95
287
{'lisi' } 1002
94
99
98
291
{'wangwu' } 1003
95
95
97
287
{'zhao' } 1004
98
95
100
293
% 合并表格
t_grade = readtable("student.xls","Sheet","grade")
Var1
ID
Chinese Math English
____________ ____ _______ ____ _______
{'zhangsan'} 1001
98
94
95
{'lisi' } 1002
94
99
98
{'wangwu' } 1003
95
95
97
t_info = readtable("student.xls","Sheet","info")
Var1
ID
Height Weight
____________ ____ ______ ______
{'zhangsan'} 1001
126
54
{'lisi' } 1002
128
56
{'wangwu' } 1003
135
55
join(t_grade,t_info)
Var1
ID
Chinese Math English Height Weight
____________ ____ _______ ____ _______ ______ ______
{'zhangsan'} 1001
98
94
95
126
54
{'lisi' } 1002
94
99
98
128
56
{'wangwu' } 1003
95
95
97
135
55
% 创建student表单,并把数据写入
writetable(t_student, 'student.xls',"Sheet", 'student')
图像处理
图片的读写和显示
% 像素点的个数对应矩阵的大小
% 矩阵元素值的范围：0：255，0：黑色，255：白色
% uint8：unsigned int 8：无符号整型
% 彩色图片是 m*n*3 的RGB三通道矩阵
pic_bw = imread("JLU.jpg")
