We have a type similar to this (a typed list) internally in pandas, although it is restricted to a single dimension and far from feature complete -- it only has .append and a .to_array() method for converting to a 1d numpy array. Our version is written in Cython, and we use it for performance reasons when we would otherwise need to create a list of unknown length: https://github.com/pydata/pandas/blob/v0.17.1/pandas/hashtable.pyx#L99 In my experience, it's several times faster than using a builtin list from Cython, which makes sense given that it needs to copy about 1/3 the data (no type or reference count for individual elements). Obviously, it uses 1/3 the space to store the data, too. We currently don't expose this object externally, but it could be an interesting project to adapt this code into a standalone project that could be more broadly useful. Cheers, Stephan On Tue, Dec 22, 2015 at 8:20 PM, Chris Barker <chris.barker@noaa.gov> wrote:
sorry for being so lazy as to not go look at the project pages, but.... This sounds like it could be really useful, and maybe supercise a coupl eof half-baked projects of mine. But -- what does "dynamic" mean? - can you append to these arrays? - can it support "ragged arrrays" -- it looks like it does.
L = ArrayList( [[0], [1,2], [3,4,5], [6,7,8,9]] ) print(L) [[0], [1 2], [3 4 5], [6 7 8 9]]
so this looks like a ragged array -- but what do you get when you do:
for row in L: print row
print(L.data) [0 1 2 3 4 5 6 7 8
is .data a regular old 1-d numpy array?
L = ArrayList( np.arange(10), [3,3,4])
print(L) [[0 1 2], [3 4 5], [6 7 8 9]] print(L.data) [0 1 2 3 4 5 6 7 8 9]
does an ArrayList act like a numpy array in other ways: L * 5 L* some_array in which case, how does it do broadcasting??? Thanks, -CHB
L = ArrayList(["Hello", "world", "!"])
print(L[0]) 'Hello' L[1] = "brave new world" print(L) ['Hello', 'brave new world', '!']
Nicolas
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-- Christopher Barker, Ph.D. Oceanographer Emergency Response Division NOAA/NOS/OR&R (206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception Chris.Barker@noaa.gov