字符串指令

• 创建字符串
  • 使用单引号将字符序列括起来创建字符串
  • 使用单引号创建的字符串是一个字符数组，每个字符都被视为一个独立的元素
    • 可以通过索引访问每个字符
  • 使用双引号创建的字符串是一个字符串数组，整个字符串被视为一个元素
    • 无法通过索引访问单个字符

>> a = "Hello World!"

a = 

    "Hello World!"

>> b = 'Hello World!'

b =

    'Hello World!'

>> b(1)

ans =

    'H'

• 拼接字符串
  • strcat
    • 水平地连接成单个字符串

>> str = strcat('Hello', 'World!')

str =

    'HelloWorld!'

• • strvcat

>> str = strvcat('Hello', 'Wrold!')

str =

  2×6 char 数组

    'Hello '
    'Wrold!'

• • char

>> str = char('Hello', 'World!')

str =

  2×6 char 数组

    'Hello '
    'World!'

• 字符串长度

>> str = 'Hello World!'

str =

    'Hello World!'

>> length(str)

ans =

    12

• 子字符串提取

>> str(2:7)

ans =

    'ello W'

• 字符串比较

str1 = 

    "Hello"

>> str2 = "Hello"

str2 = 

    "Hello"

>> str3 = "hello"

str3 = 

    "hello"

>> strcmp(str1, str2)

ans =

  logical

   1

>> strcmp(str1, str3)

ans =

  logical

   0

• 字符串查找

>> str = 'Hello James, Hello World!'

str =

    'Hello James, Hello World!'

>> str2 = 'James'

str2 =

    'James'

>> strfind(str, str2)

ans =

     7

• 字符串替换

str =

    'Hello James, Hello World!'

>> str2 = 'James'

str2 =

    'James'

>> strfind(str, str2)

ans =

     7

>> str3 = 'Potter'

str3 =

    'Potter'

>> strrep(str, str2, str3)

ans =

    'Hello Potter, Hello World!'

• 字符串转换
  • str2num函数
    • 将字符数组或字符串转换为数值数组

>> str = '123456789'

str =

    '123456789'

>> num1 = str2num(str)

num1 =

   123456789

>> num1(1)

ans =

   123456789

• • num2str函数
    • 将数值转换为字符串

>> num = 123456789

num =

   123456789

>> str = num2str(num)

str =

    '123456789'

>> str(1)

ans =

    '1'

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Matlab绘图指令

• 一维绘图

plot(x)

• 二维绘图

plot(x, y)

• 多次二维绘图

plot(x1, y1, x2, y2)

 

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>> x1 = [1, 2, 3, 4, 5, 6, 7, 8, 9];
>> y1 = [2, 3, 1, 4, 7, 3, 2, 1, 3];
>> x2 = [3, 4, 5, 6, 7, 8, 9, 10, 11 ];
>> y2 = [9, 3, 2, 3, 5, 6, 8, 2, 1];

 

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• 对数图绘制

semilogx(x1, y1)

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semilogy(x1, y1)

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loglog(x1, y1)

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• 极坐标

>> theta = linspace(0, 2*pi, 100);
>> rho = cos(theta).^2;
>> polar(theta, rho)

• 直方图

>> randnum = rand(1000);
>> hist(randnum)

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