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https://github.com/blockchain-etl/ethereum-etl.git
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86 lines
2.7 KiB
Python
86 lines
2.7 KiB
Python
# MIT License
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#
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# Copyright (c) 2018 Evgeny Medvedev, evge.medvedev@gmail.com
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in all
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# copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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import contextlib
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import csv
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import json
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import six
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from ethereumetl.csv_utils import set_max_field_size_limit
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from blockchainetl.file_utils import get_file_handle, smart_open
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@contextlib.contextmanager
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def get_item_iterable(input_file):
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fh = get_file_handle(input_file, 'r')
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if input_file.endswith('.csv'):
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set_max_field_size_limit()
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reader = csv.DictReader(fh)
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else:
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reader = (json.loads(line) for line in fh)
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try:
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yield reader
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finally:
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fh.close()
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@contextlib.contextmanager
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def get_item_sink(output_file):
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fh = get_file_handle(output_file, 'w')
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if output_file.endswith('.csv'):
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set_max_field_size_limit()
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writer = None
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def sink(item):
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nonlocal writer
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if writer is None:
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fields = list(six.iterkeys(item))
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writer = csv.DictWriter(fh, fieldnames=fields, extrasaction='ignore')
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writer.writeheader()
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writer.writerow(item)
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else:
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def sink(item):
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fh.write(json.dumps(item) + '\n')
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try:
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yield sink
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finally:
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fh.close()
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def filter_items(input_file, output_file, predicate):
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with get_item_iterable(input_file) as item_iterable, get_item_sink(output_file) as sink:
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for item in item_iterable:
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if predicate(item):
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sink(item)
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def extract_field(input_file, output_file, field):
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with get_item_iterable(input_file) as item_iterable, smart_open(output_file, 'w') as output:
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for item in item_iterable:
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output.write(item[field] + '\n')
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