[Numpy-discussion] convert array to tuples?

Christopher Barker Chris.Barker at noaa.gov
Tue Apr 5 15:35:24 EDT 2011

On 4/5/11 10:52 AM, Sebastian Haase wrote:
> How about fixing PIL... I know that there is not a good track record
> of getting patches into PIL ,
> but did you get to the bottom of it and find how draw.line is implemented?

no. I haven't. And yes adapting PIL to use the buffer interface for this 
kind of thing would be great. I also have wanted to do that for 
wxPython, where it would be welcome, but still haven't gotten around to it.

> BTW, is it drawing anti-aliased lines ?

Not with the ImageDraw module, but there is a new AggDraw module that 
should be more pretty.

On 4/5/11 11:49 AM, Mark S Niemczyk wrote:
> Just a suggestion (I am very new to Numpy), but wouldn't
> 	draw.line(tuple(points.tolist()))
> accomplish what you want.

nope, tolist() creates a list of lists -- tuple() only converts the 
outer list to a tuple, which I why I did the list comprehension.

On 4/5/11 10:53 AM, josef.pktd at gmail.com wrote:
> does a structured dtype work?

Good idea -- I'll give it a try -- indeed it does:

dt = np.dtype([('x', np.int32),('y',np.int32)])

fill="rgb(0,255,0)", width=4)

but it's not any faster, alas.

The fastest I've come up with is putting the elements in a single 1-d 
list. PIL can take either a sequence of tuples:


or the flattened version:


So this is the fastest:

draw.line(points.flatten().tolist(), fill="rgb(0,255,0)", width=4)

Thanks all,


Christopher Barker, Ph.D.

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