如何串联和索引在MATLAB细胞和数组不同？ [英] How do concatenation and indexing differ for cells and arrays in MATLAB?

问题描述

我有点困惑在MATLAB细胞和数组的使用，并愿谈几点澄清。这里是我的意见：

I am a little confused about the usage of cells and arrays in MATLAB and would like some clarification on a few points. Here are my observations:

1. 的阵列可以动态地调整它自己的存储器，以允许元件的动态数，而细胞似乎不以同样的方式起作用：

1. An array can dynamically adjust its own memory to allow for a dynamic number of elements, while cells seem to not act in the same way:

a=[]; a=[a 1]; b={}; b={b 1};

若干元素可以从细胞中进行检索，但它似乎并不像他们可以从数组：

Several elements can be retrieved from cells, but it doesn't seem like they can be from arrays:

a={'1' '2'}; figure; plot(...); hold on; plot(...); legend(a{1:2});   
b=['1' '2']; figure; plot(...); hold on; plot(...); legend(b(1:2));
%# b(1:2) is an array, not its elements, so it is wrong with legend.

这些是正确的？什么是细胞和阵列之间的一些其他不同的用途？

Are these correct? What are some other different usages between cells and array?

推荐答案

电池阵列可有点棘手，因为你可以使用 [] ，（），和的 {} 在的创建，串联和索引他们，虽然他们各自做不同的东西。解决您的两点：

Cell arrays can be a little tricky since you can use the [], (), and {} syntaxes in various ways for creating, concatenating, and indexing them, although they each do different things. Addressing your two points:

1. 要长出一个单元阵列，可以使用以下语法之一：

1. To grow a cell array, you can use one of the following syntaxes:

b = [b {1}];     %# Make a cell with 1 in it, and append it to the existing
                 %#   cell array b using []
b = {b{:} 1};    %# Get the contents of the cell array as a comma-separated
                 %#   list, then regroup them into a cell array along with a
                 %#   new value 1
b{end+1} = 1;    %# Append a new cell to the end of b using {}
b(end+1) = {1};  %# Append a new cell to the end of b using ()

在索引单元阵列与（），它返回细胞在一个单元阵列的一个子集。当指数随 {} ，它返回的逗号分隔的列表的单元格内容。例如：

When you index a cell array with (), it returns a subset of cells in a cell array. When you index a cell array with {}, it returns a comma-separated list of the cell contents. For example:

b = {1 2 3 4 5};  %# A 1-by-5 cell array
c = b(2:4);       %# A 1-by-3 cell array, equivalent to {2 3 4}
d = [b{2:4}];     %# A 1-by-3 numeric array, equivalent to [2 3 4]

有关 D 的 {} 语法提取细胞2,3的内容，和4作为< A HREF =htt​​p://www.mathworks.com/help/techdoc/matlab_prog/br2js35-1.html相对=nofollow>逗号分隔的列表，然后使用 [ ] 来收集这些值转换为数值数组。因此， B {2：4} 等同于写 B {2}，B {3}，B {4} 或 2,3,4 。

For d, the {} syntax extracts the contents of cells 2, 3, and 4 as a comma-separated list, then uses [] to collect these values into a numeric array. Therefore, b{2:4} is equivalent to writing b{2},b{3},b{4}, or 2,3,4.

对于您的来电 LEGEND ，语法传奇（{1：2}）等同于传奇（{1}，A {2}）或传奇（'1'，'2'）。这样的两个的参数（两个分开的字符）传递到传奇。语法传奇（二（1：2））传递一个参数，它是一个1×2串 '12'。

With respect to your call to LEGEND, the syntax legend(a{1:2}) is equivalent to legend(a{1},a{2}), or legend('1','2'). Thus two arguments (two separate characters) are passed to LEGEND. The syntax legend(b(1:2)) passes a single argument, which is a 1-by-2 string '12'.

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