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#!/usr/bin/env python
#
# Copyright (C) 2018 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
Merge mutliple CSV files, possibly with different columns, writing to stdout.
"""
import csv
import sys
csv_readers = [
csv.DictReader(open(csv_file, 'rb'), delimiter=',', quotechar='|')
for csv_file in sys.argv[1:]
]
# Build union of all columns from source files:
headers = set()
for reader in csv_readers:
headers = headers.union(reader.fieldnames)
# Concatenate all files to output:
out = csv.DictWriter(sys.stdout, delimiter=',', quotechar='|', fieldnames = sorted(headers))
out.writeheader()
for reader in csv_readers:
for row in reader:
out.writerow(row)
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