Use regular expression to extract a matrix from a file

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Gabriel
Gabriel 2018-5-23
回答： dpb 2018-5-23
Dear all,
I've been trying to read a matrix from a (very confusing) file, as shown below.
I am using MATLAB R2017a and the textread function with '%f%f%f%f' to read the "$Nodes" to "$EndNodes" numbers, but I had no success. What is the correct mask format to read this file as I need? More precisely, I need to extract the matrix from [1 0 0 0] to [12 0.3939339828220179 0.6060660171779821 0] in this example.
$MeshFormat
2.2 0 8
$EndMeshFormat
$Nodes
24
1 0 0 0
2 1 0 0
3 1 1 0
4 0 1 0
5 0.35 0.5 0
6 0.65 0.5 0
7 0.5 0.35 0
8 0.5 0.65 0
9 0.3939339828220177 0.393933982822018 0
10 0.6060660171779819 0.3939339828220176 0
11 0.6060660171779821 0.6060660171779821 0
12 0.3939339828220179 0.6060660171779821 0
$EndNodes
$Elements
46
1 1 2 3 1 1 2
2 1 2 4 2 2 3
3 1 2 5 3 3 4
4 1 2 4 4 4 1
5 2 2 1 1 6 20 17
6 2 2 1 1 7 15 13
7 2 2 1 1 9 14 15
$EndElements

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采纳的回答

dpb
dpb 2018-5-23
>> fid=fopen('gabe.txt');
>> a=cell2mat(textscan(fid,repmat('%f',1,4),'headerlines',5,'collectoutput',1))
a =
1.0000 0 0 0
2.0000 1.0000 0 0
3.0000 1.0000 1.0000 0
4.0000 0 1.0000 0
5.0000 0.3500 0.5000 0
6.0000 0.6500 0.5000 0
7.0000 0.5000 0.3500 0
8.0000 0.5000 0.6500 0
9.0000 0.3939 0.3939 0
10.0000 0.6061 0.3939 0
11.0000 0.6061 0.6061 0
12.0000 0.3939 0.6061 0
>> fid=fclose(fid);
If you don't know where the first record of interest is, you can find it...
fid=fopen('gabe.txt');
while isempty(strfind(fgetl(fid),'$Nodes')),end
a=cell2mat(textscan(fid,repmat('%f',1,4),'headerlines',1,'collectoutput',1));

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