Simplified version of the basic usages ofuniq(1) and sort(1), that uses a hash table internally to remove and count duplicates.
$ huniq [-c|--count] [-h|--help] < FILE > FILE
-c and --count can be used to indicate that duplicate elements should be counted. -h and --help will display this help page
This is useful for replacing the sort | uniq -c, sort | uniq or sort -u
in cases where sorting is not required.
huniq -c and huniq are both generally faster and use less memory than
their counterparts, this is achieved by using a couple of optimizations:
A hash table is used to store duplicates instead of sorting the input; this increases performance, since hashing is usually faster than sorting. It also means that duplicates do not have to be stored individually (they all occupy the same hash bucket), so the memory requirements grow with the size of the output and not the input. E.g. if each line in the input has a one duplicate at average, we need 50% less memory.
huniq also does not store the actual lines themselves, instead it just stores
a hash value (16 byte each) of that line. This is especially very useful when very
long lines are in the input.
huniq outputs lines in the order they where given, while huniq -c returns lines
in arbitrary order.
huniq does not swap data to disk like gnu sort does, so for that reason it sometimes also uses more memory than sort, especially when there are many items and not many duplicates.
Note that huniq generally has no advantage to just using
uniq without the sort, since uniq just removes consecutive
duplicates so it just needs to keep a single line in memory.
Download the submodules (git submodule init && git submodule update)
and then just type make. Move the resulting binary to a place of
your choosing in order to install.
Written by (karo@cupdev.net) Karolin Varner, for Softwear, BV (http://nl.softwear.nl/contact): You can still buy me a Club Mate. Or a coffee.
Copyright © (c) 2016, Softwear, BV. All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
- Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
- Neither the name of the Karolin Varner, Softwear, BV nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
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