I want to read a text file having strings and numeric data. Is there any better function than textscan?

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Hamza 2012-9-8

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回答： Sarah Palfreyman 2018-4-30

采纳的回答： Oleg Komarov

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Dear Users,

below are the few lines of the text which I want to display individually. It is the data of a TLE (Two-Line elements)

I want to separately read each data from the TLE. How can I do that? I want to skip the first 5 lines and start reading the data from 6th row till the end. I will be thankful if anyone can help.

=====================================================================
24652 1996-063A   ARABSAT-2B                                       
Launched: 1996-11-13 (318)           Start Date: 1996-06-12 (164)  
 Decayed:                             Stop Date: 2003-12-20 (354)  
=====================================================================
1 24652U 96063A   96318.74847837 -.00000020  00000-0  00000+0 0    14
2 24652   3.9929 210.6007 7281127 177.7757 190.4436  2.27277888    06
1 24652U 96063A   96319.62211352 -.00000020  00000-0  00000+0 0    31
2 24652   3.9929 210.3183 7284735 178.4392 185.2995  2.27373269    12
1 24652U 96063A   96319.62351606  .00008082  00000-0  30835-2 0    24
2 24652   3.9764 210.1654 7280836 178.5436 186.6267  2.27380102    20
1 24652U 96063A   96319.62356237  .00009638  00000-0  38025-2 0    37
2 24652   3.9632 210.3512 7280110 178.4006 186.6625  2.27374993    25
1 24652U 96063A   96320.05952563 -.00002597  00000-0 -98092-3 0    63
2 24652   3.9623 210.1661 7275699 178.7092 185.6294  2.27896863    39
end

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Srikanta Sharma 2012-9-8

Hi Oleg,

if your data is saved as a .txt format, then I would use the following code:

Data=dlmread('/Users/oleg/Desktop/....txt'); in order to read the .txt from line 5, Data =Data(5:end,:);

Oleg Komarov 2012-9-8

@Srikanta: dlmread() is a wrapper of textscan. Also it will not allow me to directly import the lines identified with 2 (first col) as doubles but I will have to convert.

I usually prefer to have more control on the importing procedure and try to avoid datatype conversions.

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采纳的回答

Oleg Komarov 2012-9-8

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Using textscan you can import one line and skip the next one (I save your example to test.txt).

% Import lines which start with 1

fid   = fopen('test.txt');
line1 = textscan(fid, '%f%s%s%f%f%s%s%f%f\r\n %*[^\n]','HeaderLines',5);
fclose(fid);

% Import lines which start with 2

fid   = fopen('test.txt');
line2 = textscan(fid, '%f%f%f%f%f%f%f%f%f\r\n %*[^\n]','HeaderLines',6);
fclose(fid);

The format specifier, e.g. for line 2, is '%f%f%f%f%f%f%f%f%f\r\n %*[^\n]'. Note that I read in all the values of the line, then I proceed to next line with \r\n, and I skip its content with %*[^\n]. This way I read every each line.

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Hamza 2012-9-10

Dear Oleg [num2cell(line1{:,1}) line1{:,2}] doesn't work for columns 4 and onwards.

Oleg Komarov 2012-9-10

I only gave an example for the first two columns, but you have to code all the remaining within [...].

If the column is double, then num2cell... Otherwise simply line1{:,n}.

if tou have problems extending my example post here the syntax which is not working.

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José-Luis 2012-9-8

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编辑：José-Luis 2012-9-8

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This could work:

fid = fopen('bla.txt','r');
%Advance five lines:
linesToSkip = 5;
for ii = 1:linesToSkip-1
    fgetl(fid);
end
%Process all remaining lines
tline =  fgetl(fid);
your_data = []; %You should allocate if you know how large your data is
while (~isempty(tline) )
    tline = fgetl(fid);
    %Getting rid of non-numbers
    tline = regexprep(tline,'[^0-9\s+-.eE]','');
    your_data = [your_data; str2num(tline)];
end
fclose(fid);

Note that 30835-2 is interpreted as 30833. If you want them separated then you should modify the regular expression, but then you cannot not build your_results in the same manner (some rows would have nine values, the others more). What i tried to do is to get a numeric array from your data, but you can get a cell array as well.

Maybe that is more what you want, for each tline you can get a cell array:

http://www.mathworks.com/matlabcentral/fileexchange/6054-string-to-cells

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Hamza 2012-9-9

thanks Jose-Luis

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Javier 2012-9-8

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编辑：Oleg Komarov 2012-9-8

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Hello Hamza

The first column is a dummy variable (1,2) and as Oleg says the column count in 1 and 2 are different. Next, I define the steps to get the data. Solution done in Matlab R2012a for Mac.

Step 1 Load or import file

Data=importdata('test.rtf'); %Is how text edit save data in Mac

When you do this, the data that you want to get start at row 13.

Step 2 Get the data

Case 1 Dummy value is 1

[Col1] = textscan(Data{13,1}, '%d %s %s %f %f %f %d %d %d %d %d');

For the first row data you get:

Col1=[1 '24652U' '96063A' 96318,7484783700 -2,00000000000000e-07 0 0 0 0 0 14]

Case 2 Dummy value is 2

[Col2] = textscan(Data{14,1}, '%d %s %s %f %f %f %f %f %d');
Col2 =[2 '24652' '3.9929' 210,60070 7281127 177,77570 190,44360  2,27277880 6]

If this or previous answers solve your question, please grade.

Best regards

Javier

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Javier 2012-9-9

Hi Oleg.

As I understand, there is no number 30835-2. What you could have is 30835e-2 or just two numbers 30835 and -2 (this is what I program in Matlab 2012a and it works just fine). If you work with the expression '30835-2', Matlab will interpret as a minus operation and the result will be 30833.

Oleg Komarov 2012-9-9

Please, disregard my comment above.

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Tom 2012-9-8

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What format do you want the data in? Using importdata gives you all the data as strings- you can convert the numeric data and split up the data into rows 1 and 2 easily.

%import data from txt file (using space as delimiter)
L=importdata('TLEtest.txt',' ');
%get data, ignoring first 5 lines
Data=L.textdata(6:end,:);

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Hamza 2012-9-9

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But when i'm using uiimport function to import the text file it imports correctly. The data is all correct. But when I try to run the code generated by uiimport it gives me the following error. Error using importfile (line 9) Not enough input arguments.

Code is as below: function importfile1(fileToRead1) %IMPORTFILE1(FILETOREAD1) % Imports data from the specified file % FILETOREAD1: file to read

        %  Auto-generated by MATLAB on 09-Sep-2012 15:36:41
        % Import the file
        newData1 = importdata(fileToRead1);
        % Create new variables in the base workspace from those fields.
        vars = fieldnames(newData1);
        for i = 1:length(vars)
            assignin('base', vars{i}, newData1.(vars{i}));
        end

Oleg Komarov 2012-9-9

You have to pass the 'filename' of the file you like to import, i.e. uiimport creates a function.

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Tom 2012-9-9

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This is quite scrappy but it gives you the data quite clearly in a cell array:

 n=5;    %lines to skip
A=fileread('TLETest.txt');
L=[1 regexp(A,'\n') length(A)+1]';
nLines=length(L)-n-1;
T=cell(nLines,1);
%break string of characters into rows and columns
Data=cell(nLines,9);
for ii=1:nLines
    T=A(L(n+ii):L(n+ii+1)-1);
    B=regexp(T,'\s*','Split');
    B(cellfun('isempty',B))=[];
    Data(ii,:)=B;
end