Searching for a variable in a text file & later taking its mean seperating out its units

I have a .txt file which is an output of a simulation software.I want to scan the txt file for a variable & collect that variable's value at each occurence & take its mean.

The text file is of the format:

%more text
  *****************************************************************: 
  ID : 1010
  A0 : 2.650000e+001
  A1 : 2.650000e+001
  time : 7.391000e+003 ns
  mod : 0
  sat : 0
  angle : 0.000000e+000 radians
  freq : 7.493000e+002 MHz
  count : 0
  *****************************************************************: 
  *****************************************************************: 
  ID : 1010
  A0 : 2.850000e+001
  A1 : 2.850000e+001
  time : 8.391000e+003 ns
  mod : 0
  sat : 0
  angle : 0.000000e+000 radians
  freq : 7.493000e+002 MHz
  count : 1
  *****************************************************************: 
  *****************************************************************: 
  ID : 1010
  A0 : 2.850000e+001
  A1 : 2.850000e+001
  time : 1.138600e+004 ns
  mod : 0
  sat : 0
  angle : 0.000000e+000 radians
  freq : 7.493000e+002 MHz
  count : 2
  *****************************************************************: 
  *****************************************************************: 
%more text

So for the above text file if i have to search for say freq i should get [7.493e+2 7.493e+2 7.493e+2] whose mean is 7.493e+2 MHz.

My code as of now:

fid  = fopen('ch0_TC_SYS_01.txt','r');
text = textscan(fid,'%s','Delimiter','');
text = text{1};
fid  = fclose(fid);

idx = find(~cellfun('isempty',strfind(text,'freq : ')));
text(idx)

With the above code i get something like this:

      'freq : 7.493000e+002 MHz'
      'freq : 7.493000e+002 MHz'
      'freq : 7.493000e+002 MHz'
  .........

and after this i'm doing :

        cellfun(@(x) x(8:20),abovecellarray,'un',0); 
    % & later 
        str2double;

But how can i do this dynamically seperating the units & all ?

Answer 1

[Cedric Wannaz]

I would do something like:

 content = fileread( 'ch0_TC_SYS_01.txt' ) ;
 freqStr = regexp( content, '(?<=freq : )\S+', 'match' ) ;
 freq    = str2double( freqStr ) ;

if the unit is always Mhz, and

 content = fileread( 'ch0_TC_SYS_01.txt' ) ;
 freqUnit = regexp( content, 'freq : (\S+) (\S+)', 'tokens' ) ;
 freqUnit = vertcat( freqUnit{:} ) ;
 freq     = str2double( freqUnit(:,1) ) ;
 unit     = freqUnit(:,2) ;

if you need the unit. Output of the second approach:

 >> freq
 freq =
  749.3000
  749.3000
  749.3000

 >> unit
 unit = 
    'MHz'
    'MHz'
    'MHz'

[Cedric Wannaz]

Just a little more detail about regexp ..

In the first case we ask for strings that match the pattern '(?<=freq :\s*)\S+'. This pattern is made of the following components:

• \S+ : match one or more (as many as possible) non-white-space characters,
• (?<=freq : ) : preceded by the literal 'freq : '; in regexp patterns, (?<=...) is a positive look behind for ....

In the second case we ask for parts of strings (called tokens) that match the pattern 'freq : (\S+) (\S+)'. This pattern can be described as follows: match using the pattern 'freq : \S+ \S+' where the \S+ have the same meaning as above, and we frame them in parentheses to define tokens. These tokens are what is output-ed by REGEXP (and not the whole string with the literal 'freq : '.

[Luffy]

thanks for the explanation as well.