Extracting parts of a string

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Ana Maria Alzate
Ana Maria Alzate 2018-6-15
编辑： Stephen23 2018-6-18
I have a text filewith information like this:
FileName; SampleFreq; Test;Modality;Channel;Description;StimIntensity; Position; RecordingTime
C:\Users\G10040419\Desktop\lp export application\Data 139\00000090_1.WAV; 22000; 2;1;1;5 CH Right; 0.00; -10000; 40147.491374
I need to extract the sampleFreq (22000) and the position (-10000). I tried to use regular expressions, but I cannot find specific delimiter for these data.

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采纳的回答

Paolo
Paolo 2018-6-15
编辑：Paolo 2018-6-15
The following code uses regexp to extract the data you want. You can play around with the expression here .
data = fileread('00000090Head.txt');
expression = '(?<=WAV;\s*)(\d*)(?:;\s*\d*;\d;\d;(.*?(?=;));\s*\d*\.\d*;\s*)(-?\d*)';
[tokens,match] = regexp(data,expression,'tokens','match');
sampleFrequency = cellfun(@(x) x(1,1),tokens);
position = cellfun(@(x) x(1,2),tokens);
Position and sampleFrequency are both 1x183 cell arrays and contain the data you are interested in.
position = {'-10000' '-9000' '-8000' '-7000' '-6000' '-5000' '-4500' '-4000' '-3500' '-3000' ................}
sampleFrequency = {'22000' '22000' '22000' '22000' '22000' '22000' '22000' '22000' '22000' '22000' .................}

更多回答（3 个）

per isakson
per isakson 2018-6-15
编辑：per isakson 2018-6-15
Is this what you are looking for?
fid = fopen( '00000090Head.txt', 'r' );
cac = textscan( fid, '%*s%f%*f%*f%*f%*s%*f%f%*f', 'Headerlines',1,'Delimiter',';' );
fclose( fid );
and inspect the result
>> cac
cac =
1×2 cell array
{183×1 double} {183×1 double}
>> cac{2}(1:3)
ans =
-10000
-9000
-8000
Ana Maria Alzate
Ana Maria Alzate 2018-6-15
Yes, but is not giving me the position, it is giving me the lst column, the recording time
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Jan
Jan 2018-6-15
@Ana Maria Alzate: Please do not post comments in the section for answers in the future. There is a section for comments for this job. Thanks.

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Stephen23
Stephen23 2018-6-18
编辑：Stephen23 2018-6-18
Importing the data as strings and then using regular expressions to parse them is inefficient, yet is not required because that file is very nicely formatted in delimited columns, and the required data can easily and efficiently be read directly as numeric (or char). The command textscan makes it easy specify how to read those columns, and the format string is much simpler and more intuitive that those regular expressions:
>> fmt = '%*s%f%*d%*d%*d%*s%*f%f%*f';
>> opt = {'HeaderLines',1,'Delimiter',';'};
>> [fid,msg] = fopen('00000090Head.txt','rt');
>> assert(fid>=3,msg)
>> C = textscan(fid,fmt,opt{:});
>> fclose(fid);
>> [C{:}]
ans =
22000 -10000
22000 -9000
22000 -8000
22000 -7000
22000 -6000
22000 -5000
22000 -4500
22000 -4000
22000 -3500
22000 -3000
22000 -3000
22000 -2500
22000 -2000
22000 -1500
22000 -1000
22000 -500
22000 0
22000 500
22000 1000
22000 1500
... lots of lines here
22000 -3000
22000 -2500
22000 -2000
22000 -1500
22000 -1000
22000 -500
22000 0
22000 500
22000 1000
22000 1500
22000 2000
22000 2500
22000 3000
22000 3500
22000 4000
22000 4000
22000 5000

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