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Math Forum / Math Software / MATLAB / July 2008Read Part of String
Hello, This may sound like a rediculous question, but a solution would make my day a hell of a lot easier. I have two files, for example we'll call them "F423.dat" and "F423_spectra.dat" i have written a program that will import all files in the directory (directory is a mix of .dat files and _spectra.dat files) but i'd like the program to perform different operations on the different types of files. I was wondering if MATLAB could read part of a string (namely distinguish between the normal files and the _spectra files) and sort the files accordingly? Thanks, mb Try >> infiles = ls(['F423' * '.dat']); >> file01 = deblank(infiles(1,:)); >> file02 = deblank(infiles(2,:)); Carlos "M@" <matthew.betti@gmail.com> wrote in message <ae8de555- 911d-4566-9e9f-165c2d732dba@d1g2000hsg.googlegroups.com>... > Hello, > [quoted text clipped - 11 lines] > Thanks, > mb yes, you can access strings a character at a time just like a vector of chars. Or you could use the many string parsing and searching functions. > Hello, > [quoted text clipped - 8 lines] > could read part of a string (namely distinguish between the normal > files and the _spectra files) and sort the files accordingly? help strings One alternative that comes to mind would be to do the search on "*spectra.dat" files and use the returned list instead of all files. Another depending on your OS would be something like a file specification of "f???.dat" to only return the files of form fnnn.dat Many, many choices... :) -- > Hello, > [quoted text clipped - 8 lines] > could read part of a string (namely distinguish between the normal > files and the _spectra files) and sort the files accordingly? Regular expressions? Rune Thank you all very much for the timely and very useful advice! I'm still having a problem though with the sorting. Thanks to all the input above, I can get a cell array of just the _spectra files. Although, i need a separate array of all files without the _spectra.dat files name. Namely, an array of F423.dat, F424.dat, F425.dat etc. dpb, I've tried using 'f???.dat' to no avail. > Thank you all very much for the timely and very useful advice! > [quoted text clipped - 3 lines] > _spectra.dat files name. Namely, an array of F423.dat, F424.dat, > F425.dat etc. dpb, I've tried using 'f???.dat' to no avail. Which OS? The "?" is a wildcard for a single-character match on Windows platforms; I don't know enough about unix-like shells to know what is appropriate there but I would presume there's some incantation to do the job. I can't help w/ the regexp solution as my version of Matlab predates its introduction, sorry. There would certainly be ways via the string functions in Matlab to process the full directory away and find those which contain "spectra" (findstr() comes to mind) and the remaining would be those w/o... -- > > Thank you all very much for the timely and very useful advice! > [quoted text clipped - 17 lines] > > -- I am running windows, and that "?" wildcard would certainly be what I would like to use, just to try and keep things simple. Although it does not seem to work. Is there something special about MATLAB R14 Student Version that would not allow "?" to work as a wildcard? ... > I am running windows, and that "?" wildcard would certainly be what I > would like to use, just to try and keep things simple. Although it > does not seem to work. Is there something special about MATLAB R14 > Student Version that would not allow "?" to work as a wildcard? No, it's a bug and has been around since at least Ver 5.3 (oldest I have loaded). The Matlab dir() function isn't treating the "?" as a wildcard character on Windows and passing it to the OS. However, you can work around it in the following way... >> dir('c:\temp\f*.dat') f123.dat f123_spec.dat f124.dat f124_spec.dat (Demonstrates what's in c:\temp of interest) >> [stat,d]=dos('dir /b c:\temp\f???.dat') stat = 0 d = f123.dat f124.dat -- > ... > [quoted text clipped - 23 lines] > > -- this code turns the file names to character, as opposed to strings. i.e. d(1)=f as opposed to the more useful d(1)= 'f123.dat' I'm sure there are many ways of getting characters back to strings, and i'm sorry for the hand-holding approach to coding i'm taking. I'm just the closest thing this lab has to a programmer, and thus the burden was laid. =P ... >> [stat,d]=dos('dir /b c:\temp\f???.dat') >> stat = >> 0 >> d = >> f123.dat >> f124.dat ... > this code turns the file names to character, as opposed to strings. > i.e. d(1)=f as opposed to the more useful d(1)= 'f123.dat' [quoted text clipped - 3 lines] > just the closest thing this lab has to a programmer, and thus the > burden was laid. =P I admit I didn't do anything but make sure the dos() function did end up w/ the OS "doing the right thing" so only saw the displayed output was the correct file names, not how they were returned. Turns out the names are terminated by lf character (ASCII decimal 10) so strtok() will work to return each filename from the array. Try something like r=d;while length(r)>1, [f,r]=strtok(r), end Normally would like the while condition to be something like ~isempty(r) but in this case there's a lf after the last filename also and the remainder of the string after the token is returned also contains the terminating token. Alternatively, know that, one could also be clever as the following shows... >> r=d;while ~isempty(r), [f,r]=strtok(r); r=r(2:end); disp(f), end f123.dat f124.dat ... > No, it's a bug and has been around since at least Ver 5.3 (oldest I have > loaded). The Matlab dir() function isn't treating the "?" as a wildcard > character on Windows and passing it to the OS. ... Well, that's not really stated correctly -- it appears of course that the "?" does get passed to the OS, but somehow the API used doesn't honor it. Interestingly, to see if there was something funky in the Win32 API, I tried the VB Dir$ function and it does honor it. So, either VB does a fixup or there's something not kosher about the Matlab call...wherever it actually is, it's a bug as the routine doesn't behave properly for the underlying OS... I don't think it had ever been anything I had noticed in Matlab prior to now, though... :) -- > ... >> No, it's a bug and has been around since at least Ver 5.3 (oldest I >> have loaded). The Matlab dir() function isn't treating the "?" as a >> wildcard character on Windows and passing it to the OS. ... > I don't think it had ever been anything I had noticed in Matlab prior to > now, though... :) It doesn't show as a currently listed but so I reported the anomalous behavior as a bug... -- |
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