Serialization - saving, loading and checkpointing



In [1]:

    
import mxnet as mx
from mxnet import gluon

Context



In [2]:

    
ctx = mx.cpu()

Saving and loading NDArrays



In [3]:

    
# Generate some example NDArrays
X = mx.nd.ones((100, 100))
Y = mx.nd.zeros((100, 100))



In [4]:

    
# Create a folder mimicking checkpoints
import os
os.makedirs('checkpoints', exist_ok=True)
filename = "checkpoints/test1.params"



In [5]:

    
# Save the data to a file
mx.nd.save(fname=filename, data=[X, Y])



In [6]:

    
# Load the data from a file
A, B = mx.nd.load(filename)
print(A)
print(B)









    



[[1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]
 ...
 [1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]]
<NDArray 100x100 @cpu(0)>

[[0. 0. 0. ... 0. 0. 0.]
 [0. 0. 0. ... 0. 0. 0.]
 [0. 0. 0. ... 0. 0. 0.]
 ...
 [0. 0. 0. ... 0. 0. 0.]
 [0. 0. 0. ... 0. 0. 0.]
 [0. 0. 0. ... 0. 0. 0.]]
<NDArray 100x100 @cpu(0)>



In [7]:

    
# Dictionary
# Saving a dictionary
mydict = {"X": X, "Y": Y}
filename = "checkpoints/test2.params"
mx.nd.save(filename, mydict)



In [8]:

    
# Loading the dictionary
C = mx.nd.load(filename)
print(C)









    



{'X': 
[[1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]
 ...
 [1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]]
<NDArray 100x100 @cpu(0)>, 'Y': 
[[0. 0. 0. ... 0. 0. 0.]
 [0. 0. 0. ... 0. 0. 0.]
 [0. 0. 0. ... 0. 0. 0.]
 ...
 [0. 0. 0. ... 0. 0. 0.]
 [0. 0. 0. ... 0. 0. 0.]
 [0. 0. 0. ... 0. 0. 0.]]
<NDArray 100x100 @cpu(0)>}



In [9]:

    
C['X']









    Out[9]:





[[1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]
 ...
 [1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]]
<NDArray 100x100 @cpu(0)>



In [10]:

    
C['Y']









    Out[10]:





[[0. 0. 0. ... 0. 0. 0.]
 [0. 0. 0. ... 0. 0. 0.]
 [0. 0. 0. ... 0. 0. 0.]
 ...
 [0. 0. 0. ... 0. 0. 0.]
 [0. 0. 0. ... 0. 0. 0.]
 [0. 0. 0. ... 0. 0. 0.]]
<NDArray 100x100 @cpu(0)>

Saving and loading the parameters of gluon models



In [11]:

    
# Defining a dummy network
num_hidden = 256
num_outputs = 1



In [12]:

    
net = gluon.nn.Sequential()
with net.name_scope():
    net.add(gluon.nn.Dense(units=num_hidden,
                           activation="relu"))
    net.add(gluon.nn.Dense(units=num_hidden,
                           activation="relu"))
    net.add(gluon.nn.Dense(units=num_outputs))



In [13]:

    
# Collecting parameters
net.collect_params().initialize(mx.init.Normal(sigma=1.), ctx=ctx)

At this point the parameters are not yet fully defined since we have not provided the output, nor the hard-coded shape



In [14]:

    
# First data run through the network
dummy_data = mx.nd.ones((1, 100), ctx=ctx)
net(dummy_data)









    Out[14]:





[[-2362.107]]
<NDArray 1x1 @cpu(0)>



In [15]:

    
# Saving network parameters to a file
filename = "checkpoints/testnet.params"
# Use net.save_params(filename), save_params is deprecated
net.save_parameters(filename)



In [16]:

    
# Loading the parameters into another network
net2 = gluon.nn.Sequential()
with net2.name_scope():
    net2.add(gluon.nn.Dense(units=num_hidden,
                            activation="relu"))
    net2.add(gluon.nn.Dense(units=num_hidden,
                            activation="relu"))
    net2.add(gluon.nn.Dense(units=num_outputs))



In [17]:

    
# Use net.load_parameters(), load_params is deprecated
net2.load_parameters(filename=filename,
                 ctx=ctx)



In [18]:

    
net2(dummy_data)









    Out[18]:





[[-2362.107]]
<NDArray 1x1 @cpu(0)>