| Re: Merits of different ways of 'extending' arrays [message #85862 is a reply to message #85805] |
Sat, 14 September 2013 18:11   |
Andy Sayer
Messages: 127
Registered: February 2009
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Senior Member |
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Thanks for the continuing tips!
The first suggestion (allocate a 'big enough' array up-front, rather than continually extend) worked great for my purposes, so that's what I stuck with, given that it was also very simple. Although I appreciate the continued suggestions.
Andy
On Tuesday, September 10, 2013 4:08:40 PM UTC-4, suicida...@gmail.com wrote:
> On Monday, September 9, 2013 4:41:10 PM UTC-6, suicida...@gmail.com wrote:
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>> Another option is to set up a pointer array nfiles long before the loop, inside the loop load the file and find the valid points, then put that array into that file's pointer, while incrementing a counter to keep track of the total number of points. When you're done, you have all of your data saved in pointers (one per file), and a count of the total number of valid points. Then you allocate your array, loop back through the elements of the pointer array, and fill the array as necessary. Something like:
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>> f = file_search(path, count=nfiles)
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>> ptrs = ptrarr(nfiles)
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>> num = 0l
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>> for i=0l,nfiles-1 do begin
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>> ;; load contents of file
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>> is_valid = where(stuff, n_valid)
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>> if n_valid gt 0 then begin
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>> num += n_valid
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>> ptrs[i] = ptr_new(f.var_1[is_valid])
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>> endif
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>> endfor
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>> data = fltarr(num)
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>> idx = 0l
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>> for i=0l,nfiles-1 do begin
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>> if ptr_valid(ptrs[i]) then begin
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>> num = n_elements(*ptrs[i])
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>> data[idx:idx+num-1] = *ptrs[i]
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>> ptr_free, ptrs[i]
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>> endif
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>> endfor
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> Wish I could edit my post...
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> There should be an "idx += num" next to the ptr_free at the end of the second loop.
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