[theano-users] Using symbolic vector elements as key in python OrderedDict

[Ugur Koc]

Hi,

I am a newbie for theano. I am trying to store symbolic keys and values
into a python OrderedDict as follows;
hmap=OrderedDict()
key = T.vector('key', dtype='int64')
val = T.scalar('val', dtype='int64')
minus_one=T.constant(-1, dtype='int64')

def read_map(key_):
return hmap.get(key_, minus_one)

def update_map(key_, val_):
hmap[key_]=val_
return hmap[key_]

read_map_result, _ = theano.scan(fn=read_map, sequences=[key],
outputs_info=None)
read_map_f = theano.function(inputs=[key], outputs=read_map_result)

update_map_result, updates = theano.scan(fn=update_map, sequences = [key],
non_sequences=val, outputs_info=None)
update_map_f = theano.function(inputs=[key, val],
outputs=update_map_result, updates=updates)

print(update_map_f([0, 1, 2], 5))
print(read_map_f([2]))
print(hmap)

Giving this output;

[5 5 5]

[-1]

OrderedDict([(key[t], val)])

So lookup for key 2 fails with `read_map_f`.
Any easy solution to this?

Thanks!

[Pascal Lamblin]

Unfortunately, there is no "symbolic OrderedDict" in Theano, nor is it
possible to differentiate through reading and writing to dictionaries.

You may be able to express mappings through sparse matrices, but those
are not supported on GPU.

Hi,
I am a newbie for theano. I am trying to store symbolic keys and values
into a python OrderedDict as follows;
|
hmap=OrderedDict()
key = T.vector('key', dtype='int64')
val = T.scalar('val', dtype='int64')
minus_one=T.constant(-1, dtype='int64')
return hmap.get(key_, minus_one)
hmap[key_]=val_
return hmap[key_]
read_map_result, _ = theano.scan(fn=read_map, sequences=[key],
outputs_info=None)
read_map_f = theano.function(inputs=[key], outputs=read_map_result)
update_map_result, updates = theano.scan(fn=update_map, sequences =
[key], non_sequences=val, outputs_info=None)
update_map_f = theano.function(inputs=[key, val],
outputs=update_map_result, updates=updates)
print(update_map_f([0, 1, 2], 5))
print(read_map_f([2]))
print(hmap)
|
Giving this output;
|
[5 5 5]
[-1]
OrderedDict([(key[t], val)])
|
So lookup for key 2 fails with `read_map_f`.
Any easy solution to this?
Thanks!
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