将数据块读入Matlab数组 [英] Read block of data into matlab array

问题描述

我的数据文件如下所示

3 1.0 1.4 1.7
2 1.2 1.5
1 1.1
2 1.1 1.2

对于每一行，第一个整数表示此行中的浮点数.

For each line, the first integer indicates the number of floating numbers in this line.

现在我想将所有数据加载到单个matlab数组中，并忽略第一列，也就是说，我想获得一个像这样的数组

Now I want to load all the data into a single matlab array, and ignore first column, that is, I want to get a array like this

>>arr = [1.0, 1.4, 1.7, 1.2, 1.5, 1.1, 1.1, 1.2]

如果每一行都有相同数量的浮点数，我可以这样简单地完成

if for each line, we have same number of floating numbers, I can simply do it like this

>>arr = load datafile ;
>>arr = arr(:,2:end) ; %ignore the first column
>>arr = arr(:) ; 

但是，如果每行中有不同数量的浮点数，则似乎无法直接将文件加载到矩阵中.有没有简单的方法可以做到这一点?

However, if we have different number of floating numbers in each line, it seems we cannot directly loaded the file into a matrix. Is there any simple way to accomplish this ?

谢谢.

推荐答案

首先，让我们以字符串形式读取数字:

First, let's read the numbers as strings:

C = textread('myfile.txt', '%s', 'delimiter', '\n');

结果是一个字符串单元格数组，因此让我们在每个单元格上应用str2num以获得数值:

The result is a cell-array of strings, so let's apply str2num on each cell to obtain numerical values:

C = cellfun(@str2num, C, 'Uniform', false);

现在让我们丢弃每个单元格中的第一个元素:

Now let's discard the first element from each cell:

C = cellfun(@(x)x(2:end), C, 'Uniform', false);

最后，我们将所有值连接到一个向量中:

Finally, we concatenate all values into one vector:

arr = [C{:}]

这是完整的代码:

C = textread('test.txt', '%s', 'delimiter', '\n'); %// Read data
C = cellfun(@str2num, C, 'Uniform', false);        %// Convert to numbers
C = cellfun(@(x)x(2:end), C, 'Uniform', false);    %// Remove first values
arr = [C{:}]

arr = 
    1.0000    1.4000    1.7000    1.2000    1.5000    1.1000    1.1000    1.2000

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