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Apr
5
comment Is association in mathematica ordered or not?
@Nasser: It's not the most frequent use case, but sometimes you want to aggregate data in an Association, then later process the key/value pairs in the order they were discovered. And I often find it handy that BarChart, ListPlot&friends don't jumble association data I pass them. So I'm glad Wolfram made them ordered.
Apr
5
comment Ordered associations
Not exactly a reference, but Sort and KeySort return sorted associations (and that's documented behavior). That wouldn't make any sense if associations were unordered.
Mar
24
comment Extracting road curves from an image
@P.Fonseca: I tried, but exported as gif the animation was ~30 MB... (swf and qt were both between 1-2 MB)
Mar
24
awarded  Enlightened
Mar
24
awarded  Nice Answer
Mar
24
revised Extracting road curves from an image
added 3 characters in body
Mar
24
comment Extracting road curves from an image
@Pickett: Weird. The documentation doesn't say that this syntax is new, and I could have sworn I've used it like this since v8. OTOH, the speed difference isn't that large (in this case) so I'll change it to your version.
Mar
24
comment Extracting road curves from an image
@Pickett: Weird. I've just executed the code in a fresh MMA session, and except for the Show-problem Zviovich mentioned, it worked fine. Does whitePixels contain a list of 2d coordinates in your session? Or maybe -> Automatic syntax is newer than your MMA version?
Mar
24
comment Extracting road curves from an image
@Zviovich: I've used bgnd=Image[bgnd], to make my experiments with colorDist faster. I didn't realize this changed the behavior of Show. I've updated my answer. Regarding the title: Maybe something like "Extracting road graphs from an image"?
Mar
24
revised Extracting road curves from an image
added 12 characters in body
Mar
23
answered Extracting road curves from an image
Mar
22
answered How to add a static JPEG into a Manipulate without slowing it down
Mar
19
awarded  Nice Answer
Mar
13
answered Image processing for extracting regions of book pages that are covered by text
Mar
9
comment Can I solve this graph theory problem with Mathematica?
I see. The solution got lost in translation...
Mar
9
comment Can I solve this graph theory problem with Mathematica?
Which number is which? Could you maybe draw one of them in a graph? I thought they were top-to-bottom, left-to-right, but then 4,5 in the first example would be neighbors.
Mar
4
awarded  Popular Question
Feb
20
answered Calculating displacement for a circular disc
Feb
11
comment Using 2D Fourier transform of an image to detect typical wavelengths
@SjoerdC.deVries is right, I didn't notice that. IIRC, this is done to "rotate" the 0 frequencies to the center of the FFT output. If you want to interpret the values numerically (instead of displaying the FT as a picture), you'd want to remove that line.
Feb
11
comment Using 2D Fourier transform of an image to detect typical wavelengths
fw contains the values. I.e. fw[[1,1]] is the value for frequency 0/0, fw[[1,2]] is the value for frequency 0/1...