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2019-02-12 Octave移动数据

2019-02-12 Octave移动数据

作者: 孟圆的笔记 | 来源:发表于2019-02-13 16:37 被阅读0次
>> A = [1 2; 3 4; 5 6]
A =
   1   2
   3   4
   5   6

>> size(A)
ans =
   3   2

>> sz = size(A)
sz =
   3   2

>> size(sz)
ans =
   1   2

>> size(A,1)
ans =  3

>> size(A,2)
ans =  2

>> length(A)
ans =  3

>> v = [1 2 3 4]
v =
   1   2   3   4

>> length(v)
ans =  4

 

>> pwd
ans = C:\Users\mei\Workspaces\Octave_codes

>> ls
[.]             [..]            featuresX.dat   priceY.dat

 
将dat文件加载到内存同名矩阵中:

>> load featuresX.dat
>> load priceY.dat

>> size(featuresX)
ans =
   3   2
>> size(priceY)
ans =
   3   1


>> load('featuresX.dat')
>> load('priceY.dat')

>> size(featuresX)
ans =
   3   2
>> size(priceY)
ans =
   3   1

 

查看当前Octave内存中所存储的所有变量:

>> who
A          ans        featuresX  priceY     sz         v

>> whos
   Attr Name           Size                     Bytes  Class
   ==== ====           ====                     =====  =====
        A              3x2                         48  double
        ans            1x2                         16  double
        featuresX      3x2                         48  double
        priceY         3x1                         24  double
        sz             1x2                         16  double
        v              1x4                         32  double
Total is 23 elements using 184 bytes


>> clear sz   %删除变量sz

 

存储数据到硬盘:

>> v = priceY(1:2)    %取priceY的前两条
v =
   123
   258

>> save hello.mat v    %存储变量到硬盘中,再次导入时还是原变量名,与文件名无关
>> ls
[.]             featuresX.dat   priceY.dat
[..]            hello.mat
            

>> clear  %删除内存中所有变量
>> load hello.mat  %导入
>> whos
   Attr Name        Size                     Bytes  Class
   ==== ====        ====                     =====  =====
        v           2x1                         16  double

>> v
v =
   123
   258

以上是存成了二进制格式。

 

矩阵的复杂命令:

>> 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(:,2)
ans =
   2
   4
   6

>> A([1 3], :)  %第1,3行
ans =
   1   2
   5   6

>> A([1 2 3], :)   %第1,2,3行
ans =
   1   2
   3   4
   5   6

>> A(:, [1])   %第1列
ans =
   1
   3
   5

>> A(:, [2])   %第2列
ans =
   2
   4
   6

>> A(:, [1 2])    %第1,2列
ans =
   1   2
   3   4
   5   6

>> A
A =
   1   2
   3   4
   5   6

>> A(:, 2) = [10; 11; 12]   %修改第2列
A =
    1   10
    3   11
    5   12


>> A = [A, [100;101;102]]   %为矩阵A增加一列
A =
     1    10   100
     3    11   101
     5    12   102


>> v = A(:)   %将A中所有元素一列一列存入一个列向量中
v =
     1
     3
     5
    10
    11
    12
   100
   101
   102


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

>> B = [11 22; 33 44; 55 66]
B =
   11   22
   33   44
   55   66

>> C = [A B]     %横着组合
C =
    1    2   11   22
    3    4   33   44
    5    6   55   66

>> C = [A; B]    %竖着组合
C =
    1    2
    3    4
    5    6
   11   22
   33   44
   55   66

>> [A, B]   %逗号和空格一样
ans =
    1    2   11   22
    3    4   33   44
    5    6   55   66

>> [A B]
ans =
    1    2   11   22
    3    4   33   44
    5    6   55   66

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