Organising numbers from a text file into a 2 column matrix in MATLAB -

so trying organise .txt file in matlab. file contains width , height of triangles (except first value, number of triangles). numbers organised 2nd value width , 3rd value height of triangle 1, 4th value width , 5th value height of triangle 2,and on. file starts off this.

112

5

.2

1 3

1 2 3 5

54 8

81.4724 16.2182

..........................

so question is. how matlab read file, starting second value, , organise (in case 112 x2) matrix ? also, need specify how organises data ? need fill row 1 row 2 etc.

so far have

triagnlearea = struct(width, height, area) area = 0.5*width*height fileid = fopen('sampletext','r') = fscanf('sampletext',%f) 

you have correct. when you're using fopen, need specify fileid determines access point of have opened file. specifying filename, not correct.

next, can read of values 1 single array, extract out first element number of triangles want , pull out rest of values. after, use reshape restructure array 2d matrix desire.

%// open file reading fileid = fopen('sampletext', 'r');  %// read values single array = fscanf(fileid, '%f');  %// close file fclose(fileid);  %// pull out total number of triangles numtriangles = a(1);  %// @ rest of points , reshape them %// n x 2 array values = reshape(a(2:end), 2, numtriangles).'; 

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here's example given text file. here, you've specified 12 values, there 6 triangles. such, i've made text file looks this:

6  5 .2  1 3  1 2   3 5  54 8  81.4724 16.2182 

if put above file called sampletext, both number of triangles , respective widths , heights:

>> numtriangles  numtriangles =       6  >> values  values =      5.0000    0.2000     1.0000    3.0000     1.0000    2.0000     3.0000    5.0000    54.0000    8.0000    81.4724   16.2182 

you can calculate area of each triangle using product of width , height divided 2:

>> areas = values(:,1).*values(:,2)/2  areas =      0.5000     1.5000     1.0000     7.5000   216.0000   660.6678