使用共享变量

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# -*- coding: utf-8 -*-

"""

Created on Wed Jun  4 23:28:21 2014

@author: wencc

"""

from theano import shared

from theano import function

import theano.tensor as T

if __name__ == ‘__main__‘:

state = shared(0)

inc = T.iscalar(‘inc‘)

accumulator = function([inc], state, updates=[(state, state+inc)])

print state.get_value()

print accumulator(1)

print state.get_value()

print accumulator(20)

print state.get_value()

fn_of_state = state*2 + inc

foo = T.scalar(dtype=state.dtype)

skip_shared = function([inc, foo], fn_of_state, givens=[(state, foo)])

skip_shared(1, 3)

state.get_value()

shared函数构造共享变量，共享变量的get_value,set_value函数用来查看和设置共享变量的值

function函数中的updates参数用来更新共享变量，它是一个list，list中的每一项用map（共享变量，共享变量的新值表达式）的形式来表示。