How to read csv file with asterix

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b
b on 1 May 2014
Commented: dpb on 3 May 2014
Hello,
The NOAA csv data file has the following format (showing only the first 5 rows):
USAF WBAN YR--MODAHRMN DIR SPD GUS CLG SKC L M H VSB WW WW WW W TEMP DEWP SLP ALT STP MAX MIN PCP01 PCP06 PCP24 PCPXX SD
037683 ***** 201001010020 010 10 *** 34 BKN * * * 7.0 ** ** ** * 36 30 ****** 29.56 ****** *** *** ***** ***** ***** ***** **
037683 ***** 201001010050 010 9 *** *** SCT * * * 7.0 ** ** ** * 36 30 ****** 29.56 ****** *** *** ***** ***** ***** ***** **
037683 ***** 201001010120 020 9 *** 722 SCT * * * 7.0 ** ** ** * 36 30 ****** 29.56 ****** *** *** ***** ***** ***** ***** **
037683 ***** 201001010150 360 9 *** 30 OVC * * * 7.0 ** ** ** * 36 30 ****** 29.56 ****** *** *** ***** ***** ***** ***** **
This one has 28 columns (but it can vary). It has all mixed - for example, the column 'CLG' has values [34, *, 722, 30, ...]. How to extract a particular column, and yet be able to skip the row containing the asterix data? One entire row can be asterix - which would mean that no data is available for that particular day. If the index of the skipped row containing asterix is known, that would be beneficial.
Thanks.

Accepted Answer

dpb
dpb on 1 May 2014
Actually, it's not too bad...
>> fid=fopen('noaa.csv','r');
>> l=fgetl(fid); % the header
>> toks=tokens(l);ntok=length(toks); % how many columns?
>> c=textscan(fid,repmat('%s',1,ntok),'collectoutput',true) % read that many as strings
c =
{4x28 cell}
>> fid=fclose(fid);
Now begin to do something w/ the data...
>> [~,iclg]=intersect(toks,'CLG','rows') % find a particular variable location
iclg =
7
>> clg=str2double(c{1}(:,iclg)) % convert to numeric
clg =
34
NaN
722
30
>>
find(isnan())
will return locations of missing for however you wish to deal with them.
This is one place where the cell array helps, for sure...
  5 Comments
dpb
dpb on 3 May 2014
Need to see what you actually did...the example above was R2012b here.

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