MATLAB数据处理快速学习教程

转自：/article/1820918.html

本篇内容集合了MATLAB中的基本操作、数据存储与计算、数据的直线与曲线拟合与画图、for-if-while语句的使用方法对一般matlab的操作进行了基本和详细的应用举例，非常适合初学者进行matlab学习快速掌握。下面分四个模块分别进行讲述：

========================BasicOperations========================

>> A=rand(3,2)

A =

0.8147 0.9134

0.9058 0.6324

0.1270 0.0975

>> A=[1 2;3 4;5 6]

A =

1 2

3 4

5 6

>> A(3,2)

ans =

6

>> A(2,:)

ans =

3 4

>> A([1 3],:) %select the 1st and 3rd row

ans =

1 2

5 6

>> save test.mat A

>> save testtext.txt A –ascii



>> A(:,2)=[10,11,12]

A =

1 10

3 11

5 12

>> A=[A,[101;102;103]]%append another column vector

A =

1 10 101

3 11 102

5 12 103

>> A(:)%put all elements of A into a single vector

ans =

1

3

5

10

11

12

101

102

103

B=[11,12;13,14;15,16]

B =

11 12

13 14

15 16

>> C=[A B]

C =

1 10 101 11 12

3 11 102 13 14

5 12 103 15 16

A=[1 2;3 4;5 6]

A =

1 2

3 4

5 6

>> C=[A;B]

C =

1 2

3 4

5 6

11 12

13 14

15 16

========================Computingon Data========================

>>A.*B%对应位置的数据相乘,即element product

ans =

11 24

39 56

75 96

>>A'%转置

ans =

1 3 5

2 4 6

>> A<3

ans =

1 1

0 0

0 0

>> find(A<3)

ans =

1

4

A =

8 1 6

3 5 7

4 9 2

>> [r,c]=find(A>=6)

r =

1

3

1

2

c =

1

2

3

3

a=[1 15 2 0.5]

a =

1.0000 15.0000 2.0000 0.5000

>> sum(a)

ans =

18.5000

>> prod(a)

ans =

15

>> floor(a)%取下界

ans =

1 15 2 0

>> ceil(a)%取上界

ans =

1 15 2 1

rand(3)%创建3*3的random矩阵，每个值在[0,1]之间

ans =

0.6463 0.2760 0.1626

0.7094 0.6797 0.1190

0.7547 0.6551 0.4984

>> max(rand(3),rand(3)) %在两个random的3*3矩阵中找对应位置的max

ans =

0.9597 0.2238 0.5060

0.5472 0.7513 0.8143

0.5853 0.8407 0.8909

A=magic(3)

A =

8 1 6

3 5 7

4 9 2

>> max(A,[],1) %找每列最大值，1表示第一维，即列

ans =

8 9 7

>> max(A,[],2) %找每行最大值，2表示第二维，即行

ans =

8

7

9

max(A) %defaultis column max

ans =

8 9 7

>> max(max(A))

ans =

9

>> A(:)

ans =

8

3

4

1

5

9

6

7

2

>> max(A(:))

ans =

9

>>

>>

>>

>> A=magic(9)

A =

47 58 69 80 1 12 23 34 45

57 68 79 9 11 22 33 44 46

67 78 8 10 21 32 43 54 56

77 7 18 20 31 42 53 55 66

6 17 19 30 41 52 63 65 76

16 27 29 40 51 62 64 75 5

26 28 39 50 61 72 74 4 15

36 38 49 60 71 73 3 14 25

37 48 59 70 81 2 13 24 35

>> sum(A,1)%columnsum

ans =

369 369 369 369 369 369 369 369 369

>> sum(A,2)%sumeach row

ans =

369

369

369

369

369

369

369

369

369

>> eye(9)

ans =

1 0 0 0 0 0 0 0 0

0 1 0 0 0 0 0 0 0

0 0 1 0 0 0 0 0 0

0 0 0 1 0 0 0 0 0

0 0 0 0 1 0 0 0 0

0 0 0 0 0 1 0 0 0

0 0 0 0 0 0 1 0 0

0 0 0 0 0 0 0 1 0

0 0 0 0 0 0 0 0 1

>> A.*eye(9)%takethe element product of the 2 matrix

ans =

47 0 0 0 0 0 0 0 0

0 68 0 0 0 0 0 0 0

0 0 8 0 0 0 0 0 0

0 0 0 20 0 0 0 0 0

0 0 0 0 41 0 0 0 0

0 0 0 0 0 62 0 0 0

0 0 0 0 0 0 74 0 0

0 0 0 0 0 0 0 14 0

0 0 0 0 0 0 0 0 35

>> sum(sum(A.*eye(9)))

ans =

369

>> A=magic(3)

A =

8 1 6

3 5 7

4 9 2

>> temp=pinv(A) %矩阵求逆

temp =

0.1472 -0.1444 0.0639

-0.0611 0.0222 0.1056

-0.0194 0.1889 -0.1028

>> temp*A

ans =

1.0000 -0.0000 -0.0000

-0.0000 1.0000 0.0000

0.0000 0.0000 1.0000

========================PlottingData========================

>>t=[0:0.01:0.98];

>> y1=sin(2*pi*4*t);

>> plot(t,y1)



>> hold on;%plotnew figure on the old ones

>> y2=cos(2*pi*4*t);

>> plot(t,y2,'r')



>> xlabel('time')

>> ylabel('value')

>> legend('sin','cos')

>> title('my plot')

>> print -dpng 'myplot.png'%save as a file in default catalog

>> close



%分别显示两幅图像

>> figure(1);plot(t,y1);

>> figure(2);plot(t,y2)

>>

%一幅图中显示两个subplot

figure

subplot(1,2,1);plot(t,y1)

subplot(1,2,2);plot(t,y2)

axis([0.5 1 -1 1])



A=magic(5)

imagesc(A)



>>imagesc(A),colorbar,colormap gray;



========================for if while statements========================

[cpp] view plaincopy

> v=zeros(10,1)

for i=1:10

v(i)=2^i;

end

v

v =

0

0

0

0

0

0

0

0

0

0

v =

2

4

8

16

32

64

128

256

512

1024

[cpp] view plaincopy

indices=1:10;

indices

for i=indices, disp(i);

end

i=1;

while i<=5,

v(i)=100;

i=i+1;

end;

v

i=1;

while true,

v(i)=999;

i=i+1;

if i==6,

break;

end

end

v

v(1)=2;

if v(1)==1,

disp('The value is one');

else if v(1)==2,

disp('The value is two');

else

disp('The value is neither one or two');

end

end

另外还有一些matlab高级应用：

http://emuch.net/bbs/viewthread.php?tid=4340045