How to read text line and assign value to variable?

Question

John 2018-10-15

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/424172-how-to-read-text-line-and-assign-value-to-variable

编辑： Stephen23 2018-10-16

Many tech files have header like this:

    int    display_order = 1;
    int    bigendian = 0;
    float  imagescale = 1.000000000;
    float  psi = 359.9580;
    float  phi = 0.0000;
    float  theta = 90.0000;
    float  orientation[] = {-1.0000,0.0007,-0.0000,-0.0000,-0.0000,1.0000,0.0007,1.0000,0.0000};

How can each line be assigned to the variable with value (after fgetl)?

For example: the line float

psi = 359.9580;

becomes

psi = float(359.9580);

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dpb 2018-10-15

float is not valid Matlab data type; either single or double; double is default and Matlab also is un-typed for numeric classes; integers are by default stored as double as well.

You could almost turn it into an m-file as is simply by dropping the first word of each line and rewriting; the empty [] in the array are the only thing preventing that in that sample although the curlies "{}" instead of parenetheses would create a cell array instead of a base numeric array.

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Answer 1

KSSV 2018-10-16

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/424172-how-to-read-text-line-and-assign-value-to-variable#answer_341576

在 MATLAB Online 中打开

fid = fopen('data.txt','r') ;
S = textscan(fid,'%s','delimiter','\n') ;
fclose(fid) ;
% GEt the line where psi lies 
S = S{1} ;
idx = contains(S,'psi') ;
S = S(idx) ;
S = strsplit(S{1}) ;
psi = str2num(S{4})