lightweight python wrapper for vowpal wabbit
Lightweight python wrapper for vowpal_wabbit.
Why: Scalable, blazingly fast machine learning.
make
pip install cython
python setup.py install to install.Now can you do: import vowpal_porpoise from python.
Linear regression with l1 penalty:
from vowpal_porpoise import VW
# Initialize the model
vw = VW(moniker='test', # a name for the model
passes=10, # vw arg: passes
loss='quadratic', # vw arg: loss
learning_rate=10, # vw arg: learning_rate
l1=0.01) # vw arg: l1
# Inside the with training() block a vw process will be
# open to communication
with vw.training():
for instance in ['1 |big red square',\
'0 |small blue circle']:
vw.push_instance(instance)
# here stdin will close
# here the vw process will have finished
# Inside the with predicting() block we can stream instances and
# acquire their labels
with vw.predicting():
for instance in ['1 |large burnt sienna rhombus',\
'0 |little teal oval']:
vw.push_instance(instance)
# Read the predictions like this:
predictions = list(vw.read_predictions_())
L-BFGS with a rank-5 approximation:
from vowpal_porpoise import VW
# Initialize the model
vw = VW(moniker='test_lda', # a name for the model
passes=10, # vw arg: passes
lbfgs=True, # turn on lbfgs
mem=5) # lbfgs rank
Latent Dirichlet Allocation with 100 topics:
from vowpal_porpoise import VW
# Initialize the model
vw = VW(moniker='test_lda', # a name for the model
passes=10, # vw arg: passes
lda=100, # turn on lda
minibatch=100) # set the minibatch size
Via the VW interface:
with vw.predicting_library():
for instance in ['1 |large burnt sienna rhombus', \
'1 |little teal oval']:
prediction = vw.push_instance(instance)
Now the predictions are returned directly to the parent process, rather than having to read from disk.
See examples/example1.py for more details.
Alternatively you can use the raw library interface:
import vw_c
vw = vw_c.VW("--loss=quadratic --l1=0.01 -f model")
vw.learn("1 |this is a positive example")
vw.learn("0 |this is a negative example")
vw.finish()
Currently does not support passes due to some limitations in the underlying vw C code.
vowpal_wabbit is insanely
fast and scalable. vowpal_porpoise is slower, but only during the
initial training pass. Once the data has been properly cached it will idle while vowpal_wabbit does all the heavy lifting.
Furthermore, vowpal_porpoise was designed to be lightweight and not to get in the way
of vowpal_wabbit's scalability, e.g. it allows distributed learning via
--nodes and does not require data to be batched in memory. In our
research work we use vowpal_porpoise on an 80-node cluster running over multiple
terabytes of data.
The main benefit of vowpal_porpoise is allowing rapid prototyping of new models and feature extractors. We found that we had been doing this in an ad-hoc way using python scripts to shuffle around massive gzipped text files, so we just closed the loop and made vowpal_wabbit a python library.
Wraps the vw binary in a subprocess and uses stdin to push data, temporary files to pull predictions. Why not use the prediction labels vw provides on stdout? It turns out that the python GIL basically makes streamining in and out of a process (even asynchronously) painfully difficult. If you know of a clever way to get around this, please email me. In other languages (e.g. in a forthcoming scala wrapper) this is not an issue.
Alternatively, you can use a pure api call (vw_c, wrapping libvw) for prediction.
Joseph Reisinger @josephreisinger
Apache 2.0