[WIP] Use dask.delayed within fit

.appveyor.yml

@@ -21,7 +21,7 @@ install:
   - conda info -a
   - conda create -q -n test-environment python=%PYTHON_VERSION% numpy scipy scikit-learn nose cython pandas
   - activate test-environment
-  - pip install deap tqdm update_checker pypiwin32 stopit
+  - pip install deap tqdm update_checker pypiwin32 stopit dask[delayed] git+https://github.com/dask/dask-ml
 
 
 test_script:

ci/.travis_install.sh

@@ -54,6 +54,8 @@ pip install update_checker
 pip install tqdm
 pip install stopit
 pip install xgboost
+pip install dask[delayed]
+pip install git+https://github.com/dask/dask-ml  # TODO: Change to >=0.9 when released
 
 if [[ "$COVERAGE" == "true" ]]; then
     pip install coverage coveralls

docs_sources/using.md

@@ -555,6 +555,47 @@ rmtree(cachedir)
 
 **Note: TPOT does NOT clean up memory caches if users set a custom directory path or Memory object. We recommend that you clean up the memory caches when you don't need it anymore.**
 
+# Parallel Training
+
+Internally, TPOT uses [joblib](http://joblib.readthedocs.io/) to fit estimators in parallel.
+This is the same parallelization framework used by scikit-learn.
+
+When you specify ``n_jobs``, TPOT will use ``n_jobs`` processes to fit models in parallel.
+For large problems, you can distribute the work on a [Dask](http://dask.pydata.org/en/latest/) cluster.
+There are two ways to achieve this.
+
+First, you can specify the ``use_dask`` keyword when you create the TPOT estimator.
+
+```python
+estimator = TPOTEstimator(n_jobs=-1, use_dask=True
+```
+
+This will use use all the workers on your cluster to do the training, and use [Dask-ML's pipeline rewriting](https://dask-ml.readthedocs.io/en/latest/hyper-parameter-search.html#avoid-repeated-work) to avoid re-fitting estimators multiple times on the same set of data.
+It will provide fine-grained diagnostics in the [distributed scheduler UI](https://distributed.readthedocs.io/en/latest/web.html).
+
+Alternatively, Dask implements a joblib backend.
+You can instruct TPOT to use the distribued backend during training by specifying a ``joblib.parallel_backend``:
+
+```python
+from sklearn.externals import joblib
+import distributed.joblib
+from dask.distributed import Client
+
+# connect to the cluster
+client = Client('schedueler-address')
+
+# create the estimator normally
+estimator = TPOTClassifier(n_jobs=-1)
+
+# perform the fit in this context manager
+with joblib.parallel_backend("dask"):
+    estimator.fit(X, y)
+```
+
+See [dask's distributed joblib integration](https://distributed.readthedocs.io/en/latest/joblib.html) for more.
+
+We recommend using the `use_dask` keyword.
+
 # Crash/freeze issue with n_jobs > 1 under OSX or Linux
 
 TPOT supports parallel computing for speeding up the optimization process, but it may crash/freeze with n_jobs > 1 under OSX or Linux [as scikit-learn does](http://scikit-learn.org/stable/faq.html#why-do-i-sometime-get-a-crash-freeze-with-n-jobs-1-under-osx-or-linux), especially with large datasets.

setup.py

@@ -46,7 +46,10 @@ def calculate_version():
     extras_require={
         'xgboost': ['xgboost==0.6a2'],
         'skrebate': ['skrebate>=0.3.4'],
-        'mdr': ['scikit-mdr>=0.4.4']
+        'mdr': ['scikit-mdr>=0.4.4'],
+        'dask': ['dask>=0.18.2',
+                 'distributed>=1.22.1',
+                 'dask-ml>=0.8.0'],
     },
     classifiers=[
         'Intended Audience :: Science/Research',

tests/driver_tests.py

@@ -27,19 +27,23 @@
 import sys
 from os import remove, path
 from contextlib import contextmanager
+from distutils.version import LooseVersion
 try:
     from StringIO import StringIO
 except ImportError:
     from io import StringIO
 
+import nose
 import numpy as np
 import pandas as pd
+import sklearn
 
 from tpot.driver import positive_integer, float_range, _get_arg_parser, _print_args, _read_data_file, load_scoring_function, tpot_driver
 from nose.tools import assert_raises, assert_equal, assert_in
 from unittest import TestCase
 
 
+
 @contextmanager
 def captured_output():
     new_out, new_err = StringIO(), StringIO()
@@ -169,6 +173,12 @@ def test_driver_4():
 
 def test_driver_5():
     """Assert that the tpot_driver() in TPOT driver outputs normal result with exported python file and verbosity = 0."""
+
+    # Catch FutureWarning https://github.com/scikit-learn/scikit-learn/issues/11785
+    if (np.__version__ >= LooseVersion("1.15.0") and
+            sklearn.__version__ <= LooseVersion("0.20.0")):
+        raise nose.SkipTest("Warning raised by scikit-learn")
+
     args_list = [
                 'tests/tests.csv',
                 '-is', ',',

tests/test_dask_based.py

@@ -0,0 +1,78 @@
+"""Tests that ensure the dask-based fit matches.
+
+https://github.com/DEAP/deap/issues/75
+"""
+import unittest
+
+import nose
+from sklearn.datasets import make_classification
+
+from tpot import TPOTClassifier
+
+try:
+    import dask  # noqa
+    import dask_ml  # noqa
+except ImportError:
+    raise nose.SkipTest()
+
+
+class TestDaskMatches(unittest.TestCase):
+
+    def test_dask_matches(self):
+        with dask.config.set(scheduler='single-threaded'):
+            for n_jobs in [-1]:
+                X, y = make_classification(random_state=0)
+                a = TPOTClassifier(
+                    generations=2,
+                    population_size=5,
+                    cv=3,
+                    random_state=0,
+                    n_jobs=n_jobs,
+                    use_dask=False,
+                )
+                b = TPOTClassifier(
+                    generations=2,
+                    population_size=5,
+                    cv=3,
+                    random_state=0,
+                    n_jobs=n_jobs,
+                    use_dask=True,
+                )
+                b.fit(X, y)
+                a.fit(X, y)
+
+                self.assertEqual(a.score(X, y), b.score(X, y))
+                self.assertEqual(a.pareto_front_fitted_pipelines_.keys(),
+                                 b.pareto_front_fitted_pipelines_.keys())
+                self.assertEqual(a.evaluated_individuals_,
+                                 b.evaluated_individuals_)
+
+    def test_handles_errors(self):
+        X, y = make_classification(n_samples=5)
+
+        tpot_config = {
+            'sklearn.neighbors.KNeighborsClassifier': {
+                'n_neighbors': [1, 100],
+            }
+        }
+
+        a = TPOTClassifier(
+            generations=2,
+            population_size=5,
+            cv=3,
+            random_state=0,
+            n_jobs=-1,
+            config_dict=tpot_config,
+            use_dask=False,
+        )
+        b = TPOTClassifier(
+            generations=2,
+            population_size=5,
+            cv=3,
+            random_state=0,
+            n_jobs=-1,
+            config_dict=tpot_config,
+            use_dask=True,
+        )
+        a.fit(X, y)
+        b.fit(X, y)

tpot/base.py

@@ -124,7 +124,8 @@ def __init__(self, generations=100, population_size=100, offspring_size=None,
                  random_state=None, config_dict=None,
                  warm_start=False, memory=None,
                  periodic_checkpoint_folder=None, early_stop=None,
-                 verbosity=0, disable_update_check=False):
+                 verbosity=0, disable_update_check=False,
+                 use_dask=False):
         """Set up the genetic programming algorithm for pipeline optimization.
 
         Parameters
@@ -252,6 +253,14 @@ def __init__(self, generations=100, population_size=100, offspring_size=None,
             A setting of 2 or higher will add a progress bar during the optimization procedure.
         disable_update_check: bool, optional (default: False)
             Flag indicating whether the TPOT version checker should be disabled.
+        use_dask : bool, default False
+            Whether to use Dask-ML's pipeline optimiziations. This avoid re-fitting
+            the same estimator on the same split of data multiple times. It
+            will also provide more detailed diagnostics when using Dask's
+            distributed scheduler.
+
+            See `avoid repeated work <https://dask-ml.readthedocs.io/en/latest/hyper-parameter-search.html#avoid-repeated-work>`__
+            for more.
 
         Returns
         -------
@@ -286,6 +295,7 @@ def __init__(self, generations=100, population_size=100, offspring_size=None,
         self._last_optimized_pareto_front_n_gens = 0
         self.memory = memory
         self._memory = None # initial Memory setting for sklearn pipeline
+        self.use_dask = use_dask
 
         # dont save periodic pipelines more often than this
         self._output_best_pipeline_period_seconds = 30
@@ -1190,28 +1200,48 @@ def _evaluate_individuals(self, individuals, features, target, sample_weight=Non
             scoring_function=self.scoring_function,
             sample_weight=sample_weight,
             groups=groups,
-            timeout=self.max_eval_time_seconds
+            timeout=self.max_eval_time_seconds,
+            use_dask=self.use_dask,
         )
 
         result_score_list = []
         # Don't use parallelization if n_jobs==1
-        if self.n_jobs == 1:
+        if self.n_jobs == 1 and not self.use_dask:
             for sklearn_pipeline in sklearn_pipeline_list:
                 self._stop_by_max_time_mins()
                 val = partial_wrapped_cross_val_score(sklearn_pipeline=sklearn_pipeline)
                 result_score_list = self._update_val(val, result_score_list)
         else:
             # chunk size for pbar update
             # chunk size is min of cpu_count * 2 and n_jobs * 4
-            chunk_size = min(cpu_count()*2, self.n_jobs*4)
-            for chunk_idx in range(0, len(sklearn_pipeline_list), chunk_size):
-                self._stop_by_max_time_mins()
-                parallel = Parallel(n_jobs=self.n_jobs, verbose=0, pre_dispatch='2*n_jobs')
-                tmp_result_scores = parallel(delayed(partial_wrapped_cross_val_score)(sklearn_pipeline=sklearn_pipeline)
-                                             for sklearn_pipeline in sklearn_pipeline_list[chunk_idx:chunk_idx + chunk_size])
-                # update pbar
-                for val in tmp_result_scores:
-                    result_score_list = self._update_val(val, result_score_list)
+            if self.use_dask:
+                import dask
+
+                result_score_list = [
+                    partial_wrapped_cross_val_score(sklearn_pipeline=sklearn_pipeline)
+                    for sklearn_pipeline in sklearn_pipeline_list
+                ]
+
+                self.dask_graphs_ = result_score_list
+                with warnings.catch_warnings():
+                    warnings.simplefilter('ignore')
+                    result_score_list = list(dask.compute(*result_score_list))
+
+                self._update_pbar(len(result_score_list))
+
+            else:
+                chunk_size = min(cpu_count()*2, self.n_jobs*4)
+
+                for chunk_idx in range(0, len(sklearn_pipeline_list), chunk_size):
+                    self._stop_by_max_time_mins()
+
+                    parallel = Parallel(n_jobs=self.n_jobs, verbose=0, pre_dispatch='2*n_jobs')
+                    tmp_result_scores = parallel(
+                        delayed(partial_wrapped_cross_val_score)(sklearn_pipeline=sklearn_pipeline)
+                        for sklearn_pipeline in sklearn_pipeline_list[chunk_idx:chunk_idx + chunk_size])
+                    # update pbar
+                    for val in tmp_result_scores:
+                        result_score_list = self._update_val(val, result_score_list)
 
         self._update_evaluated_individuals_(result_score_list, eval_individuals_str, operator_counts, stats_dicts)
 

tpot/gp_deap.py

@@ -23,6 +23,7 @@
 
 """
 
+import dask
 import numpy as np
 from deap import tools, gp
 from inspect import isclass
@@ -395,8 +396,10 @@ def mutNodeReplacement(individual, pset):
 
 @threading_timeoutable(default="Timeout")
 def _wrapped_cross_val_score(sklearn_pipeline, features, target,
-                             cv, scoring_function, sample_weight=None, groups=None):
+                             cv, scoring_function, sample_weight=None,
+                             groups=None, use_dask=False):
     """Fit estimator and compute scores for a given dataset split.
+
     Parameters
     ----------
     sklearn_pipeline : pipeline object implementing 'fit'
@@ -418,6 +421,8 @@ def _wrapped_cross_val_score(sklearn_pipeline, features, target,
         List of sample weights to balance (or un-balanace) the dataset target as needed
     groups: array-like {n_samples, }, optional
         Group labels for the samples used while splitting the dataset into train/test set
+    use_dask : bool, default False
+        Whether to use dask
     """
     sample_weight_dict = set_sample_weight(sklearn_pipeline.steps, sample_weight)
 
@@ -427,22 +432,50 @@ def _wrapped_cross_val_score(sklearn_pipeline, features, target,
     cv_iter = list(cv.split(features, target, groups))
     scorer = check_scoring(sklearn_pipeline, scoring=scoring_function)
 
-    try:
-        with warnings.catch_warnings():
-            warnings.simplefilter('ignore')
-            scores = [_fit_and_score(estimator=clone(sklearn_pipeline),
-                                    X=features,
-                                    y=target,
-                                    scorer=scorer,
-                                    train=train,
-                                    test=test,
-                                    verbose=0,
-                                    parameters=None,
-                                    fit_params=sample_weight_dict)
-                                for train, test in cv_iter]
-            CV_score = np.array(scores)[:, 0]
-            return np.nanmean(CV_score)
-    except TimeoutException:
-        return "Timeout"
-    except Exception as e:
-        return -float('inf')
+    if use_dask:
+        try:
+            import dask_ml.model_selection  # noqa
+            import dask  # noqa
+            from dask.delayed import Delayed
+        except ImportError:
+            msg = "'use_dask' requires the optional dask and dask-ml depedencies."
+            raise ImportError(msg)
+
+        dsk, keys, n_splits = dask_ml.model_selection._search.build_graph(
+            estimator=sklearn_pipeline,
+            cv=cv,
+            scorer=scorer,
+            candidate_params=[{}],
+            X=features,
+            y=target,
+            groups=groups,
+            fit_params=sample_weight_dict,
+            refit=False,
+            error_score=float('-inf'),
+        )
+
+        cv_results = Delayed(keys[0], dsk)
+        scores = [cv_results['split{}_test_score'.format(i)]
+                  for i in range(n_splits)]
+        CV_score = dask.delayed(np.array)(scores)[:, 0]
+        return dask.delayed(np.nanmean)(CV_score)
+    else:
+        try:
+            with warnings.catch_warnings():
+                warnings.simplefilter('ignore')
+                scores = [_fit_and_score(estimator=clone(sklearn_pipeline),
+                                         X=features,
+                                         y=target,
+                                         scorer=scorer,
+                                         train=train,
+                                         test=test,
+                                         verbose=0,
+                                         parameters=None,
+                                         fit_params=sample_weight_dict)
+                                    for train, test in cv_iter]
+                CV_score = np.array(scores)[:, 0]
+                return np.nanmean(CV_score)
+        except TimeoutException:
+            return "Timeout"
+        except Exception as e:
+            return -float('inf')