MATLAB: Extract a variable from middle of a line of a .dat file with mixed text and numbers

extract variableMATLAB

Hello.
I'm a fairly new user of MatLab and I'm having some difficulty reading data from a .dat file.I want to extract specific values from a line of the file I'm using. That line has both text and the values i want. From the sample I'm posting bellow I want to extract the values of LAT i.e. 50 55.51 and LONG i.e. -40 26.26. I would like to get 50 55.51 -40 26.26 as different variables so I can use them to convert to decimal coordinates 50.93 and -40.44, using something like this:
lat_deg = 50      % extract from file.dat



lat_min = 55.51   % extract from file.dat
lon_deg = -40      % extract from file.dat
lon_min = 26.26   % extract from file.dat
lat = lat_deg+lat_min/60
lon = lon_deg+long_min/60
_________________sample____________________________
STATION 2   DATE 1 27 1999   TIME 14:57 TO 17:08
LAT 50 55.51  LONG -40 26.26   WATER DEPTH 4060 M
   PRESS   TEMP   SALINITY  RHO(T,S,P)
    (M)     (C)   (PSS-78)  (KG M-3)
      2.   18.623   35.658   1025.35
      5.   18.627   35.657   1025.56
     10.   18.623   35.658   1025.79
The computers I use run Matlab R2008a, but sometimes I'll need to use the older Matlab 6.5 version. Any help is appreciated.
edited: to correct LAT/LONG values and indicate Matlab versions I'll be using

Best Answer

If LAT/LONG can really be anywhere in the file (not on 2nd line as shown in your sample), you could go for a regexp solution:
 >> buf = fileread('myData.dat') ;
 >> pat = 'LAT\s+(-?[\d\.])+\s+(-?[\d\.]+)\s+LONG\s+(-?[\d\.]+)\s+(-?[\d\.]+)' ;
 >> tokens = regexp(buf, pat, 'tokens') ;
 >> lat = str2double(tokens{1}(1:2))
 lat =
   50.0000   55.5100
 >> long = str2double(tokens{1}(3:4))
 long =
  -40.0000   26.2600
There are thousands of ways to implement this with REGEXP; here is another possibility:
 >> buf = fileread('myData.dat') ;
 >> match = regexp(buf, '(?<=LAT\s+)-?[\d\.]+\s+-?[\d\.]+', 'match') ;
 >> lat = str2num(match{1})
 lat =
   50.0000   55.5100
 >> match = regexp(buf, '(?<=LONG\s+)-?[\d\.]+\s+-?[\d\.]+', 'match') ;
 >> long = str2num(match{1})
 long =
  -40.0000   26.2600
Let me know if you want more information about how we are using REGEXP here.
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