diff --git a/pliers/converters/api/ibm.py b/pliers/converters/api/ibm.py
index 800112e0..846a15de 100644
--- a/pliers/converters/api/ibm.py
+++ b/pliers/converters/api/ibm.py
@@ -4,13 +4,14 @@
 import base64
 import json
 import logging
+from urllib.parse import urlencode
+from urllib.request import Request, urlopen
+from urllib.error import URLError, HTTPError
+
 from pliers.stimuli.text import TextStim, ComplexTextStim
 from pliers.utils import attempt_to_import, verify_dependencies
 from pliers.converters.audio import AudioToTextConverter
 from pliers.transformers.api import APITransformer
-from urllib.parse import urlencode
-from urllib.request import Request, urlopen
-from urllib.error import URLError, HTTPError
 
 sr = attempt_to_import('speech_recognition', 'sr')
 
diff --git a/pliers/converters/api/wit.py b/pliers/converters/api/wit.py
index e0d673af..86de385c 100644
--- a/pliers/converters/api/wit.py
+++ b/pliers/converters/api/wit.py
@@ -3,12 +3,13 @@
 import logging
 import os
 from abc import abstractproperty
+from urllib.request import Request, urlopen
+from urllib.error import HTTPError
+
 from pliers.stimuli.text import ComplexTextStim
 from pliers.utils import attempt_to_import, verify_dependencies
 from pliers.converters.audio import AudioToTextConverter
 from pliers.transformers.api import APITransformer
-from urllib.request import Request, urlopen
-from urllib.error import HTTPError
 
 sr = attempt_to_import('speech_recognition', 'sr')
 
diff --git a/pliers/converters/base.py b/pliers/converters/base.py
index 2ff1256d..9547ae4a 100644
--- a/pliers/converters/base.py
+++ b/pliers/converters/base.py
@@ -1,11 +1,12 @@
 ''' Base Converter class and utilities. '''
 
 from abc import ABCMeta, abstractmethod, abstractproperty
+import inspect
+
 from pliers.transformers import Transformer
 from pliers.utils import listify, EnvironmentKeyMixin
 from pliers import config
 import pliers
-import inspect
 
 
 class Converter(Transformer, metaclass=ABCMeta):
diff --git a/pliers/converters/image.py b/pliers/converters/image.py
index 827cd3dc..e0033c07 100644
--- a/pliers/converters/image.py
+++ b/pliers/converters/image.py
@@ -1,10 +1,11 @@
 ''' Converter classes that operate on ImageStim inputs. '''
 
 from PIL import Image
-from .base import Converter
+
 from pliers.stimuli.image import ImageStim
 from pliers.stimuli.text import TextStim
 from pliers.utils import attempt_to_import, verify_dependencies
+from .base import Converter
 
 pytesseract = attempt_to_import('pytesseract')
 
diff --git a/pliers/extractors/api/clarifai.py b/pliers/extractors/api/clarifai.py
index 5e2d56be..a757a24d 100644
--- a/pliers/extractors/api/clarifai.py
+++ b/pliers/extractors/api/clarifai.py
@@ -5,13 +5,16 @@
 import logging
 import os
 from contextlib import ExitStack
+
+import pandas as pd
+
 from pliers.extractors.image import ImageExtractor
 from pliers.extractors.video import VideoExtractor
 from pliers.extractors.base import ExtractorResult
 from pliers.transformers import BatchTransformerMixin
 from pliers.transformers.api import APITransformer
 from pliers.utils import listify, attempt_to_import, verify_dependencies
-import pandas as pd
+
 
 clarifai_client = attempt_to_import('clarifai.rest.client', 'clarifai_client',
                                     ['ClarifaiApp',
diff --git a/pliers/extractors/api/google.py b/pliers/extractors/api/google.py
index 0d848390..7e1f4c82 100644
--- a/pliers/extractors/api/google.py
+++ b/pliers/extractors/api/google.py
@@ -1,5 +1,14 @@
 ''' Google API-based feature extraction classes. '''
 
+import logging
+import time
+import warnings
+import os
+from collections import defaultdict
+
+import numpy as np
+import pandas as pd
+
 from pliers.extractors.image import ImageExtractor
 from pliers.extractors.text import TextExtractor
 from pliers.extractors.video import VideoExtractor
@@ -8,13 +17,6 @@
                                  GoogleAPITransformer)
 from pliers.extractors.base import ExtractorResult
 from pliers.utils import flatten_dict
-import numpy as np
-import pandas as pd
-import logging
-import time
-import warnings
-import os
-from collections import defaultdict
 
 
 class GoogleVisionAPIExtractor(GoogleVisionAPITransformer, ImageExtractor):
diff --git a/pliers/extractors/api/microsoft.py b/pliers/extractors/api/microsoft.py
index 0b12e4be..2ca7da80 100644
--- a/pliers/extractors/api/microsoft.py
+++ b/pliers/extractors/api/microsoft.py
@@ -2,13 +2,13 @@
 Extractors that interact with Microsoft Azure Cognitive Services API.
 '''
 
+import pandas as pd
+
 from pliers.extractors.base import ExtractorResult
 from pliers.extractors.image import ImageExtractor
 from pliers.transformers import (MicrosoftAPITransformer,
                                  MicrosoftVisionAPITransformer)
 
-import pandas as pd
-
 
 class MicrosoftAPIFaceExtractor(MicrosoftAPITransformer, ImageExtractor):
     ''' Extracts face features (location, emotion, accessories, etc.). From an
diff --git a/pliers/extractors/audio.py b/pliers/extractors/audio.py
index 189aac71..e2ef812f 100644
--- a/pliers/extractors/audio.py
+++ b/pliers/extractors/audio.py
@@ -1,18 +1,21 @@
 ''' Extractors that operate on AudioStim inputs. '''
+
+from abc import ABCMeta
+from os import path
+import sys
+import logging
+
+import numpy as np
+from scipy import fft
+import pandas as pd
+import soundfile as sf
+
 from pliers.stimuli.audio import AudioStim
 from pliers.stimuli.text import ComplexTextStim
 from pliers.extractors.base import Extractor, ExtractorResult
 from pliers.utils import attempt_to_import, verify_dependencies, listify
 from pliers.support.exceptions import MissingDependencyError
 from pliers.support.setup_yamnet import YAMNET_PATH
-import numpy as np
-from scipy import fft
-import pandas as pd
-import soundfile as sf
-from abc import ABCMeta
-from os import path
-import sys
-import logging
 
 librosa = attempt_to_import('librosa')
 tf = attempt_to_import('tensorflow')
diff --git a/pliers/extractors/base.py b/pliers/extractors/base.py
index f725775f..563d9041 100644
--- a/pliers/extractors/base.py
+++ b/pliers/extractors/base.py
@@ -1,12 +1,14 @@
 ''' Base Extractor class and associated functionality. '''
 
 from abc import ABCMeta, abstractmethod
+import json
+
 import pandas as pd
 import numpy as np
+from pandas.api.types import is_numeric_dtype
+
 from pliers.transformers import Transformer
 from pliers.utils import isgenerator, flatten, listify
-from pandas.api.types import is_numeric_dtype
-import json
 
 
 class Extractor(Transformer, metaclass=ABCMeta):
diff --git a/pliers/extractors/image.py b/pliers/extractors/image.py
index 64724230..65163441 100644
--- a/pliers/extractors/image.py
+++ b/pliers/extractors/image.py
@@ -2,14 +2,15 @@
 Extractors that operate primarily or exclusively on Image stimuli.
 '''
 
+from functools import partial
+
+import numpy as np
+import pandas as pd
+
 from pliers.stimuli.image import ImageStim
 from pliers.extractors.base import Extractor, ExtractorResult
 from pliers.utils import attempt_to_import, verify_dependencies, listify
 from pliers.support.due import due, Url, Doi
-import numpy as np
-import pandas as pd
-from functools import partial
-
 
 cv2 = attempt_to_import('cv2')
 face_recognition = attempt_to_import('face_recognition')
diff --git a/pliers/extractors/models.py b/pliers/extractors/models.py
index 0ef5aacf..eaab63e8 100644
--- a/pliers/extractors/models.py
+++ b/pliers/extractors/models.py
@@ -1,12 +1,12 @@
 ''' Extractor classes based on pre-trained models. '''
 
 import numpy as np
+
 from pliers.extractors.image import ImageExtractor
 from pliers.extractors.base import ExtractorResult
 from pliers.filters.image import ImageResizingFilter
 from pliers.utils import attempt_to_import, verify_dependencies
 
-
 tf = attempt_to_import('tensorflow')
 attempt_to_import('tensorflow.keras')
 
diff --git a/pliers/extractors/text.py b/pliers/extractors/text.py
index 092df326..7d17ba2a 100644
--- a/pliers/extractors/text.py
+++ b/pliers/extractors/text.py
@@ -2,6 +2,15 @@
 Extractors that operate primarily or exclusively on Text stimuli.
 '''
 import sys
+import itertools
+import logging
+
+import numpy as np
+import pandas as pd
+import scipy
+import nltk
+from nltk.sentiment.vader import SentimentIntensityAnalyzer
+
 from pliers.stimuli.text import TextStim, ComplexTextStim
 from pliers.extractors.base import Extractor, ExtractorResult
 from pliers.support.exceptions import PliersError
@@ -10,13 +19,6 @@
 from pliers.transformers import BatchTransformerMixin
 from pliers.utils import (attempt_to_import, verify_dependencies, flatten,
     listify)
-import itertools
-import numpy as np
-import pandas as pd
-import scipy
-import nltk
-from nltk.sentiment.vader import SentimentIntensityAnalyzer
-import logging
 
 
 keyedvectors = attempt_to_import('gensim.models.keyedvectors', 'keyedvectors',
diff --git a/pliers/extractors/video.py b/pliers/extractors/video.py
index 962ea975..038656c8 100644
--- a/pliers/extractors/video.py
+++ b/pliers/extractors/video.py
@@ -2,12 +2,12 @@
 Extractors that operate primarily or exclusively on Video stimuli.
 '''
 
+import numpy as np
+
 from pliers.stimuli.video import VideoStim
 from pliers.extractors.base import Extractor, ExtractorResult
 from pliers.utils import attempt_to_import, verify_dependencies
 
-import numpy as np
-
 cv2 = attempt_to_import('cv2')
 
 
diff --git a/pliers/filters/audio.py b/pliers/filters/audio.py
index ef9d544e..d5dffb90 100644
--- a/pliers/filters/audio.py
+++ b/pliers/filters/audio.py
@@ -1,9 +1,10 @@
 ''' Filters that operate on TextStim inputs. '''
 
+from copy import deepcopy
+
 from pliers.stimuli import AudioStim
 from pliers.utils import attempt_to_import, verify_dependencies
 from .base import Filter, TemporalTrimmingFilter
-from copy import deepcopy
 
 librosa = attempt_to_import('librosa')
 
diff --git a/pliers/filters/base.py b/pliers/filters/base.py
index 707b9f44..bd3d2f70 100644
--- a/pliers/filters/base.py
+++ b/pliers/filters/base.py
@@ -1,12 +1,12 @@
 ''' Base Filter class and associated functionality. '''
 
 from abc import ABCMeta, abstractmethod
+import logging
+
 from pliers.stimuli import AudioStim, VideoStim
 from pliers.transformers import Transformer
 from pliers.utils import listify
 
-import logging
-
 
 class Filter(Transformer, metaclass=ABCMeta):
     ''' Base class for Filters.'''
diff --git a/pliers/filters/image.py b/pliers/filters/image.py
index 28f85da0..34aae65e 100644
--- a/pliers/filters/image.py
+++ b/pliers/filters/image.py
@@ -1,11 +1,11 @@
 ''' Filters that operate on ImageStim inputs. '''
 
-from pliers.stimuli.image import ImageStim
+import numpy as np
 from PIL import Image
 from PIL import ImageFilter as PillowFilter
-from .base import Filter
 
-import numpy as np
+from pliers.stimuli.image import ImageStim
+from .base import Filter
 
 
 class ImageFilter(Filter):
diff --git a/pliers/filters/text.py b/pliers/filters/text.py
index 395e65b0..2f791329 100644
--- a/pliers/filters/text.py
+++ b/pliers/filters/text.py
@@ -1,13 +1,14 @@
 ''' Filters that operate on TextStim inputs. '''
 
-import nltk
 import string
 import re
 
+import nltk
 from nltk import stem
 from nltk.tokenize import word_tokenize
 from nltk.tokenize import * # noqa
 from nltk.tokenize.api import TokenizerI
+
 from pliers.stimuli.text import TextStim
 from pliers.support.decorators import requires_nltk_corpus
 from .base import Filter
diff --git a/pliers/filters/video.py b/pliers/filters/video.py
index 309af916..0f265087 100644
--- a/pliers/filters/video.py
+++ b/pliers/filters/video.py
@@ -1,12 +1,11 @@
 ''' Filters that operate on TextStim inputs. '''
 
+import numpy as np
+
 from pliers.stimuli.video import VideoStim, VideoFrameCollectionStim
 from pliers.utils import attempt_to_import, verify_dependencies
 from .base import Filter, TemporalTrimmingFilter
 
-import numpy as np
-
-
 cv2 = attempt_to_import('cv2')
 
 
diff --git a/pliers/graph.py b/pliers/graph.py
index cfcbb965..9f0b41d8 100644
--- a/pliers/graph.py
+++ b/pliers/graph.py
@@ -1,15 +1,14 @@
 ''' The `graph` module contains tools for constructing and executing graphs
 of pliers Transformers. '''
+from itertools import chain
+from collections import OrderedDict
+import json
 
 from pliers.extractors.base import merge_results
 from pliers.stimuli import __all__ as stim_list
 from pliers.transformers import get_transformer
 from pliers.utils import (listify, flatten, isgenerator, attempt_to_import,
                           verify_dependencies)
-from itertools import chain
-from collections import OrderedDict
-
-import json
 
 pgv = attempt_to_import('pygraphviz', 'pgv')
 stim_list.insert(0, 'ExtractorResult')
diff --git a/pliers/stimuli/audio.py b/pliers/stimuli/audio.py
index af7454cd..9a750c04 100644
--- a/pliers/stimuli/audio.py
+++ b/pliers/stimuli/audio.py
@@ -1,9 +1,10 @@
 ''' Classes that represent audio clips. '''
 
-from .base import Stim
 from moviepy.audio.io.AudioFileClip import AudioFileClip
 from moviepy.video.io.ffmpeg_reader import ffmpeg_parse_infos
 
+from .base import Stim
+
 
 class AudioStim(Stim):
 
diff --git a/pliers/stimuli/base.py b/pliers/stimuli/base.py
index 3b71a594..35618deb 100644
--- a/pliers/stimuli/base.py
+++ b/pliers/stimuli/base.py
@@ -1,6 +1,5 @@
 ''' Base class for all Stims and associated functionality. '''
 
-
 from abc import ABCMeta, abstractmethod
 from os.path import isdir, join, basename, realpath, isfile
 from glob import glob
@@ -8,13 +7,15 @@
 from urllib.parse import urlparse
 from collections import namedtuple
 from contextlib import contextmanager
-from pliers import config
-from pliers.utils import isiterable
-import pandas as pd
 import os
 import tempfile
 import base64
 
+import pandas as pd
+
+from pliers import config
+from pliers.utils import isiterable
+
 
 class Stim(metaclass=ABCMeta):
 
diff --git a/pliers/stimuli/image.py b/pliers/stimuli/image.py
index b8f594a1..5859a9a8 100644
--- a/pliers/stimuli/image.py
+++ b/pliers/stimuli/image.py
@@ -1,13 +1,15 @@
 ''' Classes that represent images. '''
 
-from .base import Stim
-from imageio import imread, imsave
-from PIL import Image
+from functools import lru_cache
 from urllib.request import urlopen
 import io
+
+from imageio import imread, imsave
+from PIL import Image
 import numpy as np
-from functools import lru_cache
+
 from .base import _get_bytestring
+from .base import Stim
 
 
 class ImageStim(Stim):
diff --git a/pliers/stimuli/text.py b/pliers/stimuli/text.py
index b029627f..d53288a2 100644
--- a/pliers/stimuli/text.py
+++ b/pliers/stimuli/text.py
@@ -1,8 +1,10 @@
 ''' Classes that represent text or sequences of text. '''
 
 import re
-import pandas as pd
 from urllib.request import urlopen
+
+import pandas as pd
+
 from pliers.support.decorators import requires_nltk_corpus
 from pliers.utils import attempt_to_import, verify_dependencies
 from .base import Stim
diff --git a/pliers/stimuli/video.py b/pliers/stimuli/video.py
index acdc6701..debe0483 100644
--- a/pliers/stimuli/video.py
+++ b/pliers/stimuli/video.py
@@ -2,7 +2,9 @@
 
 from __future__ import division
 from math import ceil
+
 from moviepy.video.io.VideoFileClip import VideoFileClip
+
 from .base import Stim, _get_bytestring
 from .audio import AudioStim
 from .image import ImageStim
diff --git a/pliers/support/decorators.py b/pliers/support/decorators.py
index 500ce2ce..fbbfb281 100644
--- a/pliers/support/decorators.py
+++ b/pliers/support/decorators.py
@@ -2,6 +2,7 @@
 """Custom decorators."""
 from __future__ import absolute_import
 from functools import wraps
+
 from pliers.support.exceptions import MissingCorpusError
 
 
diff --git a/pliers/tests/converters/api/test_google_converters.py b/pliers/tests/converters/api/test_google_converters.py
index 6a9fdfbb..a541e405 100644
--- a/pliers/tests/converters/api/test_google_converters.py
+++ b/pliers/tests/converters/api/test_google_converters.py
@@ -1,9 +1,11 @@
 from os.path import join
+
+import pytest
+
 from ...utils import get_test_data_path
 from pliers.converters import (GoogleVisionAPITextConverter,
                                GoogleSpeechAPIConverter)
 from pliers.stimuli import ImageStim, AudioStim, ComplexTextStim
-import pytest
 
 IMAGE_DIR = join(get_test_data_path(), 'image')
 AUDIO_DIR = join(get_test_data_path(), 'audio')
diff --git a/pliers/tests/converters/api/test_ibm_converters.py b/pliers/tests/converters/api/test_ibm_converters.py
index b975125c..3757f5f0 100644
--- a/pliers/tests/converters/api/test_ibm_converters.py
+++ b/pliers/tests/converters/api/test_ibm_converters.py
@@ -1,9 +1,11 @@
 from os.path import join
+
+import pytest
+
 from ...utils import get_test_data_path
 from pliers import config
 from pliers.converters import IBMSpeechAPIConverter
 from pliers.stimuli import AudioStim, TextStim, ComplexTextStim
-import pytest
 
 AUDIO_DIR = join(get_test_data_path(), 'audio')
 
diff --git a/pliers/tests/converters/api/test_microsoft_converters.py b/pliers/tests/converters/api/test_microsoft_converters.py
index a7b6806e..34c04303 100644
--- a/pliers/tests/converters/api/test_microsoft_converters.py
+++ b/pliers/tests/converters/api/test_microsoft_converters.py
@@ -1,8 +1,10 @@
 from os.path import join
+
+import pytest
+
 from ...utils import get_test_data_path
 from pliers.converters import MicrosoftAPITextConverter
 from pliers.stimuli import ImageStim
-import pytest
 
 IMAGE_DIR = join(get_test_data_path(), 'image')
 
diff --git a/pliers/tests/converters/api/test_revai_converters.py b/pliers/tests/converters/api/test_revai_converters.py
index 95c9c839..70905dc0 100644
--- a/pliers/tests/converters/api/test_revai_converters.py
+++ b/pliers/tests/converters/api/test_revai_converters.py
@@ -1,8 +1,10 @@
 from os.path import join
+
+import pytest
+
 from ...utils import get_test_data_path
 from pliers.converters import RevAISpeechAPIConverter
 from pliers.stimuli import AudioStim, ComplexTextStim, TextStim
-import pytest
 
 AUDIO_DIR = join(get_test_data_path(), 'audio')
 
diff --git a/pliers/tests/converters/api/test_wit_converters.py b/pliers/tests/converters/api/test_wit_converters.py
index f82f3fa1..865bfb79 100644
--- a/pliers/tests/converters/api/test_wit_converters.py
+++ b/pliers/tests/converters/api/test_wit_converters.py
@@ -1,8 +1,10 @@
 from os.path import join
+
+import pytest
+
 from ...utils import get_test_data_path
 from pliers.converters import WitTranscriptionConverter
 from pliers.stimuli import AudioStim, TextStim, ComplexTextStim
-import pytest
 
 AUDIO_DIR = join(get_test_data_path(), 'audio')
 
diff --git a/pliers/tests/converters/test_converters.py b/pliers/tests/converters/test_converters.py
index 0ce68914..a52a8cdf 100644
--- a/pliers/tests/converters/test_converters.py
+++ b/pliers/tests/converters/test_converters.py
@@ -1,4 +1,7 @@
 from os.path import join
+
+import pytest
+
 from ..utils import get_test_data_path
 from pliers.converters import (get_converter,
                                VideoToAudioConverter,
@@ -8,7 +11,6 @@
 from pliers.converters.image import ImageToTextConverter
 from pliers.stimuli import (VideoStim, TextStim,
                             ComplexTextStim, ImageStim)
-import pytest
 
 
 def test_get_converter():
diff --git a/pliers/tests/converters/test_image_converters.py b/pliers/tests/converters/test_image_converters.py
index fecc7369..1e787bfb 100644
--- a/pliers/tests/converters/test_image_converters.py
+++ b/pliers/tests/converters/test_image_converters.py
@@ -1,8 +1,10 @@
 from os.path import join
+
+import pytest
+
 from ..utils import get_test_data_path
 from pliers.converters import TesseractConverter
 from pliers.stimuli import ImageStim
-import pytest
 
 IMAGE_DIR = join(get_test_data_path(), 'image')
 
diff --git a/pliers/tests/converters/test_video_converters.py b/pliers/tests/converters/test_video_converters.py
index 5745f6a4..09244941 100644
--- a/pliers/tests/converters/test_video_converters.py
+++ b/pliers/tests/converters/test_video_converters.py
@@ -1,8 +1,10 @@
 from os.path import join
+
+import numpy as np
+
 from ..utils import get_test_data_path
 from pliers.converters import VideoToAudioConverter
 from pliers.stimuli import VideoStim
-import numpy as np
 
 VIDEO_DIR = join(get_test_data_path(), 'video')
 
diff --git a/pliers/tests/extractors/api/test_clarifai_extractors.py b/pliers/tests/extractors/api/test_clarifai_extractors.py
index 5c3de226..1cdf5570 100644
--- a/pliers/tests/extractors/api/test_clarifai_extractors.py
+++ b/pliers/tests/extractors/api/test_clarifai_extractors.py
@@ -1,12 +1,14 @@
 from os.path import join
+
+import numpy as np
+import pytest
+
 from ...utils import get_test_data_path
 from pliers import config
 from pliers.extractors import (ClarifaiAPIImageExtractor,
                                ClarifaiAPIVideoExtractor)
 from pliers.extractors.base import merge_results
 from pliers.stimuli import ImageStim, VideoStim
-import numpy as np
-import pytest
 
 IMAGE_DIR = join(get_test_data_path(), 'image')
 VIDEO_DIR = join(get_test_data_path(), 'video')
diff --git a/pliers/tests/extractors/api/test_google_extractors.py b/pliers/tests/extractors/api/test_google_extractors.py
index 943934b2..1e043c8a 100644
--- a/pliers/tests/extractors/api/test_google_extractors.py
+++ b/pliers/tests/extractors/api/test_google_extractors.py
@@ -1,3 +1,9 @@
+import json
+from os.path import join
+
+import pytest
+import numpy as np
+
 from pliers import config
 from pliers.filters import FrameSamplingFilter
 from pliers.extractors import (GoogleVisionAPIFaceExtractor,
@@ -20,11 +26,8 @@
 from pliers.extractors.api.google import GoogleVisionAPIExtractor
 from pliers.stimuli import ImageStim, VideoStim, TextStim
 from pliers.utils import attempt_to_import, verify_dependencies
-import pytest
-import json
-from os.path import join
 from ...utils import get_test_data_path
-import numpy as np
+
 
 googleapiclient = attempt_to_import('googleapiclient', fromlist=['discovery'])
 
diff --git a/pliers/tests/extractors/api/test_microsoft_extractors.py b/pliers/tests/extractors/api/test_microsoft_extractors.py
index c08418fe..75cbf907 100644
--- a/pliers/tests/extractors/api/test_microsoft_extractors.py
+++ b/pliers/tests/extractors/api/test_microsoft_extractors.py
@@ -1,3 +1,7 @@
+from os.path import join
+
+import pytest
+
 from pliers import config
 from pliers.extractors import (MicrosoftAPIFaceExtractor,
                                MicrosoftAPIFaceEmotionExtractor,
@@ -9,8 +13,6 @@
                                MicrosoftVisionAPIAdultExtractor)
 from pliers.extractors import merge_results
 from pliers.stimuli import ImageStim, VideoStim
-import pytest
-from os.path import join
 from ...utils import get_test_data_path
 
 IMAGE_DIR = join(get_test_data_path(), 'image')
diff --git a/pliers/tests/extractors/test_audio_extractors.py b/pliers/tests/extractors/test_audio_extractors.py
index 6ff4309d..92a647ad 100644
--- a/pliers/tests/extractors/test_audio_extractors.py
+++ b/pliers/tests/extractors/test_audio_extractors.py
@@ -1,5 +1,9 @@
 from os.path import join
 from os import environ
+
+import numpy as np
+import pytest
+
 from ..utils import get_test_data_path
 from pliers.extractors import (LibrosaFeatureExtractor,
                                STFTAudioExtractor,
@@ -30,8 +34,7 @@
                             TranscribedAudioCompoundStim)
 from pliers.filters import AudioResamplingFilter
 from pliers.utils import attempt_to_import, verify_dependencies
-import numpy as np
-import pytest
+
 
 AUDIO_DIR = join(get_test_data_path(), 'audio')
 tf = attempt_to_import('tensorflow')
diff --git a/pliers/tests/extractors/test_extractors.py b/pliers/tests/extractors/test_extractors.py
index f672fb2c..b1c7e9cd 100644
--- a/pliers/tests/extractors/test_extractors.py
+++ b/pliers/tests/extractors/test_extractors.py
@@ -1,4 +1,9 @@
 from os.path import join
+import json
+
+import numpy as np
+import pytest
+
 from pliers.tests.utils import (get_test_data_path, DummyExtractor, 
                                 ClashingFeatureExtractor)
 from pliers.extractors import (LengthExtractor,
@@ -10,9 +15,6 @@
 from pliers.support.download import download_nltk_data
 from pliers.extractors.base import ExtractorResult, merge_results
 from pliers import config
-import numpy as np
-import pytest
-import json
 
 TEXT_DIR = join(get_test_data_path(), 'text')
 
diff --git a/pliers/tests/extractors/test_image_extractors.py b/pliers/tests/extractors/test_image_extractors.py
index 110483d7..85f5048a 100644
--- a/pliers/tests/extractors/test_image_extractors.py
+++ b/pliers/tests/extractors/test_image_extractors.py
@@ -1,4 +1,8 @@
 from os.path import join
+
+import numpy as np
+import pytest
+
 from ..utils import get_test_data_path
 from pliers.extractors import (BrightnessExtractor,
                                SharpnessExtractor,
@@ -10,8 +14,7 @@
                                FaceRecognitionFaceEncodingsExtractor)
 from pliers.stimuli import ImageStim
 from pliers.extractors.base import merge_results
-import numpy as np
-import pytest
+
 
 IMAGE_DIR = join(get_test_data_path(), 'image')
 
diff --git a/pliers/tests/extractors/test_text_extractors.py b/pliers/tests/extractors/test_text_extractors.py
index 3af007bd..a3ac8f9f 100644
--- a/pliers/tests/extractors/test_text_extractors.py
+++ b/pliers/tests/extractors/test_text_extractors.py
@@ -1,3 +1,14 @@
+
+from os.path import join
+from pathlib import Path
+from os import environ
+import shutil
+
+import numpy as np
+import pytest
+import spacy
+from transformers import BertTokenizer
+
 from pliers import config
 from pliers.extractors import (DictionaryExtractor,
                                PartOfSpeechExtractor,
@@ -16,14 +27,7 @@
 from pliers.extractors.base import merge_results
 from pliers.stimuli import TextStim, ComplexTextStim
 from pliers.tests.utils import get_test_data_path
-import numpy as np
-from os.path import join
-from pathlib import Path
-import shutil
-import pytest
-import spacy
-from os import environ
-from transformers import BertTokenizer
+
 
 TEXT_DIR = join(get_test_data_path(), 'text')
 
diff --git a/pliers/tests/extractors/test_video_extractors.py b/pliers/tests/extractors/test_video_extractors.py
index 452e00cb..01a05c18 100644
--- a/pliers/tests/extractors/test_video_extractors.py
+++ b/pliers/tests/extractors/test_video_extractors.py
@@ -1,9 +1,11 @@
 from os.path import join
+
+import numpy as np
+import pytest
+
 from ..utils import get_test_data_path
 from pliers.extractors import FarnebackOpticalFlowExtractor
 from pliers.stimuli import VideoStim
-import numpy as np
-import pytest
 
 VIDEO_DIR = join(get_test_data_path(), 'video')
 
diff --git a/pliers/tests/filters/test_audio_filters.py b/pliers/tests/filters/test_audio_filters.py
index 99f9ce10..12e4cee6 100644
--- a/pliers/tests/filters/test_audio_filters.py
+++ b/pliers/tests/filters/test_audio_filters.py
@@ -1,11 +1,13 @@
 from os.path import join
+
+import pytest
+import numpy as np
+
 from ..utils import get_test_data_path
 from pliers.filters import (AudioTrimmingFilter, 
                             TemporalTrimmingFilter,
                             AudioResamplingFilter)
 from pliers.stimuli import AudioStim
-import pytest
-import numpy as np
 
 AUDIO_DIR = join(get_test_data_path(), 'audio')
 
diff --git a/pliers/tests/filters/test_image_filters.py b/pliers/tests/filters/test_image_filters.py
index 67059670..7da52318 100644
--- a/pliers/tests/filters/test_image_filters.py
+++ b/pliers/tests/filters/test_image_filters.py
@@ -1,11 +1,13 @@
 from os.path import join
+
+import numpy as np
+import pytest
+
 from ..utils import get_test_data_path
 from pliers.filters import (ImageCroppingFilter,
                             ImageResizingFilter,
                             PillowImageFilter)
 from pliers.stimuli import ImageStim
-import numpy as np
-import pytest
 
 IMAGE_DIR = join(get_test_data_path(), 'image')
 
diff --git a/pliers/tests/filters/test_text_filters.py b/pliers/tests/filters/test_text_filters.py
index 91b5a98d..f0c77dd1 100644
--- a/pliers/tests/filters/test_text_filters.py
+++ b/pliers/tests/filters/test_text_filters.py
@@ -1,4 +1,11 @@
 from os.path import join
+import string
+
+from nltk import stem as nls
+from nltk.tokenize import PunktSentenceTokenizer
+import nltk
+import pytest
+
 from ..utils import get_test_data_path
 from pliers.filters import (WordStemmingFilter,
                             TokenizingFilter,
@@ -7,11 +14,6 @@
                             PunctuationRemovalFilter)
 from pliers.graph import Graph
 from pliers.stimuli import ComplexTextStim, TextStim
-from nltk import stem as nls
-from nltk.tokenize import PunktSentenceTokenizer
-import nltk
-import pytest
-import string
 
 
 TEXT_DIR = join(get_test_data_path(), 'text')
diff --git a/pliers/tests/filters/test_video_filters.py b/pliers/tests/filters/test_video_filters.py
index 8ce2d7e8..2c472414 100644
--- a/pliers/tests/filters/test_video_filters.py
+++ b/pliers/tests/filters/test_video_filters.py
@@ -1,11 +1,14 @@
 from os.path import join
+import math
+
+import pytest
+
 from ..utils import get_test_data_path
 from pliers.filters import (FrameSamplingFilter,
                             VideoTrimmingFilter,
                             TemporalTrimmingFilter)
 from pliers.stimuli import VideoStim, VideoFrameStim
-import pytest
-import math
+
 
 VIDEO_DIR = join(get_test_data_path(), 'video')
 
diff --git a/pliers/tests/test_config.py b/pliers/tests/test_config.py
index 45fb587a..69e350eb 100644
--- a/pliers/tests/test_config.py
+++ b/pliers/tests/test_config.py
@@ -1,8 +1,10 @@
-import pliers
 import tempfile
 import os
 import json
+
 import pytest
+
+import pliers
 from pliers.config import reset_options
 
 
diff --git a/pliers/tests/test_datasets.py b/pliers/tests/test_datasets.py
index 11528500..1eebceea 100644
--- a/pliers/tests/test_datasets.py
+++ b/pliers/tests/test_datasets.py
@@ -1,6 +1,7 @@
-from pliers.datasets.text import _load_datasets
 import requests
 
+from pliers.datasets.text import _load_datasets
+
 
 def test_dicts_exist_at_url_and_initialize():
     """
diff --git a/pliers/tests/test_diagnostics.py b/pliers/tests/test_diagnostics.py
index 68717c33..06751469 100644
--- a/pliers/tests/test_diagnostics.py
+++ b/pliers/tests/test_diagnostics.py
@@ -1,5 +1,6 @@
 import pandas as pd
 import numpy as np
+
 from pliers.diagnostics import Diagnostics
 from pliers.diagnostics import correlation_matrix
 from pliers.diagnostics import eigenvalues
diff --git a/pliers/tests/test_graph.py b/pliers/tests/test_graph.py
index 38c732ce..70a2b0dc 100644
--- a/pliers/tests/test_graph.py
+++ b/pliers/tests/test_graph.py
@@ -1,4 +1,11 @@
+from os.path import join, exists
+import tempfile
+import os
+
+from numpy.testing import assert_almost_equal
+import pandas as pd
 import pytest
+
 from pliers.graph import Graph, Node
 from pliers.converters import (TesseractConverter,
                                VideoToAudioConverter,
@@ -8,11 +15,6 @@
                                LengthExtractor, merge_results)
 from pliers.stimuli import (ImageStim, TextStim, VideoStim)
 from .utils import get_test_data_path, DummyExtractor
-from os.path import join, exists
-from numpy.testing import assert_almost_equal
-import pandas as pd
-import tempfile
-import os
 
 
 def test_node_init():
diff --git a/pliers/tests/test_io.py b/pliers/tests/test_io.py
index cc75e255..9bc0ef33 100644
--- a/pliers/tests/test_io.py
+++ b/pliers/tests/test_io.py
@@ -1,8 +1,9 @@
-from .utils import get_test_data_path
-from pliers.stimuli import load_stims
 from os.path import join
+
 import pytest
 
+from .utils import get_test_data_path
+from pliers.stimuli import load_stims
 
 def test_magic_loader():
     text_file = join(get_test_data_path(), 'text', 'sample_text.txt')
diff --git a/pliers/tests/test_scikit.py b/pliers/tests/test_scikit.py
index 8651d68c..0120c939 100644
--- a/pliers/tests/test_scikit.py
+++ b/pliers/tests/test_scikit.py
@@ -1,14 +1,15 @@
-from .utils import get_test_data_path
+from os.path import join
 
 import pytest
 import numpy as np
 
-from os.path import join
 from pliers.extractors import BrightnessExtractor, SharpnessExtractor
 from pliers.graph import Graph
 from pliers.utils.scikit import PliersTransformer
 from pliers.stimuli import ImageStim
 
+from .utils import get_test_data_path
+
 
 def test_graph_scikit():
     pytest.importorskip('pytesseract')
diff --git a/pliers/tests/test_stims.py b/pliers/tests/test_stims.py
index bf72aa58..cb399d08 100644
--- a/pliers/tests/test_stims.py
+++ b/pliers/tests/test_stims.py
@@ -1,3 +1,12 @@
+import tempfile
+import os
+import base64
+from os.path import join, exists
+
+import numpy as np
+import pandas as pd
+import pytest
+
 from .utils import get_test_data_path
 from pliers.stimuli import (VideoStim, VideoFrameStim, ComplexTextStim,
                             AudioStim, ImageStim, CompoundStim,
@@ -10,13 +19,6 @@
                                ComplexTextExtractor)
 from pliers.extractors.base import Extractor, ExtractorResult
 from pliers.support.download import download_nltk_data
-import numpy as np
-from os.path import join, exists
-import pandas as pd
-import pytest
-import tempfile
-import os
-import base64
 
 
 class DummyExtractor(Extractor):
diff --git a/pliers/tests/test_transformers.py b/pliers/tests/test_transformers.py
index 10c4ff94..8134c19b 100644
--- a/pliers/tests/test_transformers.py
+++ b/pliers/tests/test_transformers.py
@@ -1,13 +1,16 @@
+from os.path import join
+
+import numpy as np
+import pytest
+
 from pliers.transformers import get_transformer
 from pliers.extractors import (STFTAudioExtractor, BrightnessExtractor,
                                merge_results)
 from pliers.stimuli.base import TransformationLog
 from pliers.stimuli import ImageStim, VideoStim, TextStim
 from pliers import config
-from os.path import join
+
 from .utils import get_test_data_path, DummyExtractor, DummyBatchExtractor
-import numpy as np
-import pytest
 
 
 def test_get_transformer_by_name():
diff --git a/pliers/tests/test_updater.py b/pliers/tests/test_updater.py
index 9dedabc7..46b4b6c1 100644
--- a/pliers/tests/test_updater.py
+++ b/pliers/tests/test_updater.py
@@ -1,7 +1,10 @@
-from pliers.utils.updater import check_updates
 from tempfile import NamedTemporaryFile
+
 import pandas as pd
 
+from pliers.utils.updater import check_updates
+
+
 def test_updater():
     datastore_file = NamedTemporaryFile().name
     transformers = [('BrightnessExtractor', {}), ('TesseractConverter', {})]
diff --git a/pliers/tests/test_utils.py b/pliers/tests/test_utils.py
index 3192b150..9c79160b 100644
--- a/pliers/tests/test_utils.py
+++ b/pliers/tests/test_utils.py
@@ -1,11 +1,14 @@
+from types import GeneratorType
+from os.path import join
+
+import pytest
+
 from pliers.stimuli import VideoStim
 from pliers.filters import FrameSamplingFilter
 from pliers.utils import batch_iterable, flatten_dict
 from pliers import config
-from types import GeneratorType
+
 from .utils import get_test_data_path
-from os.path import join
-import pytest
 
 
 @pytest.mark.skip(reason="tqdm prevents normal stdout/stderr capture; need to"
diff --git a/pliers/tests/utils.py b/pliers/tests/utils.py
index 2e517313..3c75e5ec 100644
--- a/pliers/tests/utils.py
+++ b/pliers/tests/utils.py
@@ -1,10 +1,13 @@
 from os.path import dirname, join
+from copy import deepcopy
+
+import numpy as np
+import pandas as pd
+
 from pliers.stimuli import ImageStim
 from pliers.extractors.base import Extractor, ExtractorResult
 from pliers.transformers import BatchTransformerMixin
-import numpy as np
-from copy import deepcopy
-import pandas as pd
+
 
 def get_test_data_path():
     """Returns the path to test datasets """
diff --git a/pliers/transformers/api/base.py b/pliers/transformers/api/base.py
index 22204327..6cf06445 100644
--- a/pliers/transformers/api/base.py
+++ b/pliers/transformers/api/base.py
@@ -1,9 +1,9 @@
 ''' Base implementation for all API transformers. '''
+import time
 
 from pliers import config
 from pliers.transformers import Transformer
 from pliers.utils import isiterable, listify, APIDependent
-import time
 
 
 class APITransformer(APIDependent, Transformer):
diff --git a/pliers/transformers/api/google.py b/pliers/transformers/api/google.py
index c7ff3781..bf9254b7 100644
--- a/pliers/transformers/api/google.py
+++ b/pliers/transformers/api/google.py
@@ -1,5 +1,6 @@
 import logging
 import os
+
 from pliers.transformers import BatchTransformerMixin
 from pliers.transformers.api import APITransformer
 from pliers.utils import attempt_to_import, verify_dependencies
diff --git a/pliers/transformers/api/microsoft.py b/pliers/transformers/api/microsoft.py
index ba1a1864..1ecddc6c 100644
--- a/pliers/transformers/api/microsoft.py
+++ b/pliers/transformers/api/microsoft.py
@@ -1,6 +1,8 @@
 import logging
 import os
+
 import requests
+
 from pliers.transformers.api import APITransformer
 
 
diff --git a/pliers/transformers/base.py b/pliers/transformers/base.py
index c0886c5a..6a33d9e1 100644
--- a/pliers/transformers/base.py
+++ b/pliers/transformers/base.py
@@ -1,4 +1,8 @@
 ''' Core transformer logic. '''
+from abc import ABCMeta, abstractmethod, abstractproperty
+import importlib
+import logging
+from functools import wraps
 
 from pliers import config
 from pliers.stimuli.base import Stim, _log_transformation, load_stims
@@ -7,10 +11,7 @@
                           isgenerator, listify, batch_iterable,
                           attempt_to_import, set_iterable_type)
 import pliers
-from abc import ABCMeta, abstractmethod, abstractproperty
-import importlib
-import logging
-from functools import wraps
+
 
 multiprocessing = attempt_to_import('pathos.multiprocessing',
                                     'multiprocessing', ['ProcessingPool'])
diff --git a/pliers/utils/base.py b/pliers/utils/base.py
index 1b0a59c8..2adf2f84 100644
--- a/pliers/utils/base.py
+++ b/pliers/utils/base.py
@@ -3,11 +3,13 @@
 import collections
 import os
 from abc import ABCMeta, abstractmethod, abstractproperty
+from types import GeneratorType
+from itertools import islice
+
 from tqdm import tqdm
+
 from pliers import config
 from pliers.support.exceptions import MissingDependencyError
-from types import GeneratorType
-from itertools import islice
 
 
 def listify(obj):
diff --git a/pliers/utils/updater.py b/pliers/utils/updater.py
index f914a1bc..43230265 100644
--- a/pliers/utils/updater.py
+++ b/pliers/utils/updater.py
@@ -2,13 +2,16 @@
 
 import glob
 import datetime
+from os.path import realpath, join, dirname, exists, expanduser
+import hashlib
+import pickle
+
 import pandas as pd
 import numpy as np
-from os.path import realpath, join, dirname, exists, expanduser
+
 from pliers.stimuli import load_stims
 from pliers.transformers import get_transformer
-import hashlib
-import pickle
+
 
 def hash_data(data, blocksize=65536):
     """" Hashes list of data, strings or data """