MATLAB: Extract data from a text data.

text file

Hi all!

i have a text file. it is constructed like this:

input start1
 a:12 b:1.5 c:1.75 d:0.25
 a:52 b:3.5 c:2.75 d:0.75
 a:12 b:1.5 c:1.75 d:0.25
...
...
...
a:12 b:1.5 c:1.75 d:0.25
output end1
input start2
 a:12 b:1.5 c:1.75 d:0.25
 a:52 b:3.5 c:2.75 d:0.75
 a:12 b:1.5 c:1.75 d:0.25
...
...
...
a:12 b:0 c:1.752 d:0.225
output end2
input start3
..
...
...
...

How could read this text file? imean i want just th parameter a b c d .

thank you

Best Answer

fid=fopen('file.txt','r');
text=textscan(fid,'a:%f b:%f c:%f d:%f \n');
fclose(fid);

text will be a 1*4 cell array, where text{1,1} is the vector of all your a, where text{1,2} is the vector of all your b...

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MATLAB: Error using cat. Dimensions of arrays being concatenated are not consistent.

That is not very well designed code: the regexp is overkill, and the str2num with cellfun is likely not very efficient (as well as hiding evil eval inside...).

The code below imports the header into a structure hdr and the numeric data into matrix out (with class single to save memory):

str = fileread('zero_mac_cluster1.asc');
str = strrep(str,',','.');
% Parse Header:
opt = {'MultipleDelimsAsOne',true};
hdr = textscan(str,'%s%f',6,opt{:});
hdr = cell2struct(num2cell(hdr{2}),hdr{1});
% Parse Matrix:
opt = {'HeaderLines',numel(fieldnames(hdr)), 'CollectOutput',true};
fmt = repmat('%f32',1,hdr.ncols);
out = textscan(str,fmt,opt{:});
out = out{1};
out(out==hdr.NODATA_value) = NaN;

And checking:

>> hdr
hdr = 
           ncols: 10139
           nrows: 7013
       xllcorner: 1557267.2310345
       yllcorner: 4850030.77
        cellsize: 10
    NODATA_value: -9999
>> size(out) % matches the file rows, which is NOT what the header states!
ans =
        6065       10139
>> out(~isnan(out))
ans =
              10
            1.25
           21.75
           24.25
           22.25
            1.25
            6.25
           24.25
               0
           38.25
             7.5
            1.75
               1
            1.25
            0.25
            2.25
               7
            0.25
           36.75
             0.5
               0
            20.5
            2.75
           22.25
             4.5
             1.5
            3.25
            1.75
            0.25
               0
            1.25
             2.5
           30.25
           27.25
            2.75
               0
               1
       0.3846154
            0.75
               1
            3.75
        12.77778
           28.75
              12
               0
        3.181818
             1.5
               0
             5.5
              12
        66.92308
               0
               0
            1.75
            0.25
               0
               5
           45.75
            9.75
               0
            20.5
           24.25
               0
           19.75
            2.25
               0
               1
            23.5
               0
               0
            0.25
               1
               0
              12
        21.38889
            1.75
       0.2777778
            34.5
               8
             0.5
            0.25
           16.75
               4
               0
             -99
            2.25
             2.5
           45.25
            0.25
               0
             5.5
            2.25
            3.75
            3.75
            6.75
               0
            1.75

Note that the memory requirements are not insignificant:

>> whos out
  Name         Size                   Bytes  Class     Attributes
  out       6065x10139            245972140  single

MATLAB: Function definition is misplaced or improperly nested error

Once the code is aligned properly then the problem is clear:

for ...
    for ...
        for ...
            for ...
                for ...
                    for ...
                        for ...
                            ...
                            function dvdy = dstate(y,v)
                            v = ([c0]/v^2)-([c1]/v)-([c2]*y/v)-[c3]-[c4].*v^0.75-[c5]*v-([c6]*v/(sqrt(a^2-(y-0.047)^2)));% This is ODE
                            end
                        end
                    end
                end
            end
        end
    end
end

Functions cannot be defined inside of loops or of any other code constructs. They can be defined at file level only.

You will need to replace that invalid function definition with an anonymous function:

https://www.mathworks.com/help/matlab/matlab_prog/anonymous-functions.html

Note that your code contains many syntax warnings that I strongly suggest that you fix.

Best Answer

Related Solutions

MATLAB: Error using cat. Dimensions of arrays being concatenated are not consistent.

MATLAB: Function definition is misplaced or improperly nested error

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