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April 11, 2021 15:14
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Get top 10 lines in large file
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| import unittest | |
| import sys, array, tempfile, heapq | |
| import io | |
| from itertools import islice | |
| NUM_LINES_IN_MEM_PER_FILE = 100000 | |
| NUM_LINES_IN_EACH_FILE = 1000000 | |
| class SortLargeFile: | |
| def intsfromfile(self, f): | |
| while True: | |
| next_n_lines = list(islice(f, NUM_LINES_IN_MEM_PER_FILE)) | |
| if not next_n_lines: | |
| break | |
| for line in next_n_lines: | |
| yield line | |
| f.close() | |
| def saveToTemp(self, arr): | |
| print("size of the arr {}".format(len(arr))) | |
| f = tempfile.TemporaryFile(mode="r+") | |
| li = list(sorted(arr)) | |
| f.writelines(i for i in li) | |
| f.seek(0) | |
| return self.intsfromfile(f) | |
| def sort(self, source): | |
| print('source {}'.format(source)) | |
| iters = [] | |
| with open(source, 'r') as sf: | |
| arr = [] | |
| for line in sf: | |
| arr.append(line) | |
| if len(arr) >= NUM_LINES_IN_EACH_FILE: | |
| iters += self.saveToTemp(arr) | |
| arr = [] | |
| if arr: | |
| iters += self.saveToTemp(arr) | |
| print('Number of tmp files', len(iters)) | |
| last = None | |
| count = 0 | |
| top_ten = [] | |
| for x in heapq.merge(*iters): | |
| count += 1 | |
| if not last or last != x: | |
| if not last: | |
| last=x.strip('\n') | |
| if len(top_ten) < 10: | |
| heapq.heappush(top_ten, (count,last)) | |
| elif top_ten[0][0] < count or (top_ten[0][0] == count and top_ten[0][1] < last): | |
| heapq.heappushpop(top_ten, (count,last)) | |
| last = x | |
| count = 0 | |
| if len(top_ten) < 10 or top_ten[0][0] < count: | |
| heapq.heappushpop(top_ten, (count,last)) | |
| while top_ten: | |
| val = heapq.heappop(top_ten) | |
| print(val[1], val[0]) | |
| slf = SortLargeFile() | |
| slf.sort('/Users/drichards/grabbag/test_mocking.py/hash_keys_small.txt') |
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