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Last Post 01 Mar 2009 05:47 AM by anon

problem in ENVI_OPEN_FILE

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anon

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01 Mar 2009 05:47 AM
Hello, I encounter a problem in IDL programing. I use ENVI_OPEN_FILE, inputfilename, r_fid = t_fid and I "help t_fid" T_FID LONG = Array[3] and I "print t_fid" 32 12 2 if (t_fid eq -1) then begin IDL tell me expression mus be a scalar or 1 element arra in this context: below is from the HELP ENVI_OPEN_FILE fname = '/data/img_001' envi_open_file, fname, r_fid=fid if (fid eq -1) then return envi_file_query, fid, dims=dims, nb=nb why this happened , what should I do?

Deleted User

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01 Mar 2009 08:01 PM
I run my code in ENVI 4.3 and the problem, so I check my code carefully, and I can not find any mistakes, Then I try it in ENVI 4.5 ,there is no problem. I do not know why this happened.

MariM

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02 Mar 2009 02:00 PM
I would think both versions of ENVI would give you an error message, as they did for me. This is because you are opening a file that contains multiple files and thus multiple FIDs. So your returned FID from opening the file is an array. However, in your IF statement, you reference FID as a scalar. Instead, you would do something like: ENVI> if(fid[0] eq -1) then return Which will test if the first element of the FID array is -1, or whichever element you want. You should only need to test one element to see if it is valid.

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