import a module with parameter in python
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21-12-2019 - |
문제
Is it possible to pass import a module with some parameter in python ?
All I mean by parameter is that there exists a variable in the module which is not initialized in that module, still I am using that variable in that module. In short, I want behaviour similar to function but unlike function, I want the variables of module to be exposed in the calling code.
eg
a.py
#lists like data, count, prob_distribution are constructed from training_pool (not initialized in this file)
x = pymc.Uniform('x', lower = 0, upper = 1)
rv = [ Multinomial("rv"+str(i), count[i], prob_distribution[i], value = data[i], observed=True) for i in xrange(0, len(count)) ]
b.py
import a #I want some way tr pass value of training_pool
m = pymc.MCMC(a)
I want all random variables in a.py to be exposed to MCMC. I am open to a better approach for my problem at hand, but I would also like to know whteher passing arguments to modules is possible in python or not
해결책
As @otus already answered, there is no way to pass parameters to modules.
I think you are following some of the introductory examples for PyMC2, which use a pattern where a module wraps all the code for the nodes in a Bayesian model. This approach is good for getting started, but, as you have found, can be limiting, when you want to run your model with a range of variations.
Fortunately, PyMC2 can create an MCMC object from a list or a dictionary as well as a module. What I recommend in this case is just what @oleg-s suggested in the comments: use a function. You can end the function with return locals()
to get a dictionary of everything that would have been in the module, and this is suitable input to the pymc.MCMC
constructor. Here is an example:
# a.py
from pymc import *
count = [10, 10] # perhaps good to put this stuff in data.py
prob_distribution = [[.5, .5], [.1, .2, .7]]
data = [[2, 8], [2, 3, 5]]
def model(training_pool):
x = Uniform('x', lower = 0, upper = 1)
rv = [ Multinomial("rv"+str(i), count[i], prob_distribution[i], value = data[i], observed=True) for i in training_pool ]
return locals()
# b.py
import pymc, a
training_pool = [0]
m = pymc.MCMC(a.model(training_pool))
다른 팁
There is no way to pass parameters to modules. However, you could use a global in a third module for this:
# a.py
parameter = None
# b.py
import a
a.parameter = 4
import c
# c.py
import a
# use a.parameter
Of course, this only works if nothing else imports c, because modules only get imported once.
there are various approaches to do so, here is just a silly and simple one:
main.py
"""A silly example - main supplies a parameter
"""
import sys,os
print os.path.basename(__file__)+":Push it by: --myModuleParam "+str(123)
sys.argv.append('--myModuleParam')
sys.argv.append(123)
import module
print os.path.basename(__file__)+":Pushed my param:"+str(module.displayMyParam)
module.py
"""A silly example - module consumes parameter
"""
import sys,os
displayMyParam = 'NotYetInitialized'
for px in sys.argv:
if px == '--myModuleParam':
idx = sys.argv.index(px)
sys.argv.pop(idx) # remove option
displayMyParam = sys.argv[idx]
sys.argv.pop(idx) # remove value
print os.path.basename(__file__)+":Got my param:"+str(displayMyParam)
#
# That's it...
#
I found it helpful to define global variables, and allow these to be set by an init function.
def init(config_filename=CONFIG_FILENAME):
config = configparser.ConfigParser(interpolation=configparser.ExtendedInterpolation())
config.read(config_filename)
global YEARS
YEARS = config['DEFAULT']['YEARS']
global FEATURES
FEATURES = config['DEFAULT']['FEATURES']
Then all the user has to do is remember to initialize the module before using these methods:
import module
module.init('config.ini')
Note, I would NOT use this on a module that I expect to spread publicly. This is more for single-file modules for my own personal use.