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

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Luffy
Luffy 2015-9-29
评论： Luffy 2015-9-30
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 ?

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Cedric
Cedric 2015-9-29
编辑：Cedric 2015-9-29
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'
  2 个评论
Cedric
Cedric 2015-9-29
编辑：Cedric 2015-9-29
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 : '.

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