bitarray | 易学教程

C/C++ Bit Array or Bit Vector

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问题 I am learning C/C++ programming & have encountered the usage of 'Bit arrays' or 'Bit Vectors'. Am not able to understand their purpose? here are my doubts - Are they used as boolean flags? Can one use int arrays instead? (more memory of course, but..) What's this concept of Bit-Masking? If bit-masking is simple bit operations to get an appropriate flag, how do one program for them? is it not difficult to do this operation in head to see what the flag would be, as apposed to decimal numbers? I

Auto increment in MongoDB to store sequence of Unique User ID

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I am making a analytics system, the API call would provide a Unique User ID, but it's not in sequence and too sparse. I need to give each Unique User ID an auto increment id to mark a analytics datapoint in a bitarray/bitset. So the first user encounters would corresponding to the first bit of the bitarray, second user would be the second bit in the bitarray, etc. So is there a solid and fast way to generate incremental Unique User IDs in MongoDB? Konstantin Pribluda You can, but you should not https://web.archive.org/web/20151009224806/http://docs.mongodb.org/manual/tutorial/create-an-auto

How do I represent and work with n-bit vectors in Python?

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问题 In an assignment I am currently working on we need to work with bit vectors, but I am very unsure of how to do this in Python. They should be able to be from 4 bits to 20 bits. I have never worked with bit vector before, but I guess that one would one create arrays of unsigned bytes that you manipulated using the usual AND/OR/XOR operations. The important restriction here is: I cannot rely on any libraries other than those supplied with standard Python. I think I know how I would do this in C

Does Python have a bitfield type?

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I need a compact representation of an array of booleans, does Python have a builtin bitfield type or will I need to find an alternate solution? Bitarray was the best answer I found, when I recently had a similar need. It's a C extension (so much faster than BitVector, which is pure python) and stores its data in an actual bitfield (so it's eight times more memory efficient than a numpy boolean array, which appears to use a byte per element.) nealmcb If you mainly want to be able to name your bit fields and easily manipulate them, e.g. to work with flags represented as single bits in a

Convert from BitArray to Byte

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问题 I have a BitArray with the length of 8, and I need a function to convert it to a byte . How to do it? Specifically, I need a correct function of ConvertToByte : BitArray bit = new BitArray(new bool[] { false, false, false, false, false, false, false, true }); //How to write ConvertToByte byte myByte = ConvertToByte(bit); var recoveredBit = new BitArray(new[] { myByte }); Assert.AreEqual(bit, recoveredBit); 回答1: This should work: byte ConvertToByte(BitArray bits) { if (bits.Count != 8) { throw

How to define and work with an array of bits in C?

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问题 I want to create a very large array on which I write \'0\'s and \'1\'s. I\'m trying to simulate a physical process called random sequential adsorption, where units of length 2, dimers, are deposited onto an n-dimensional lattice at a random location, without overlapping each other. The process stops when there is no more room left on the lattice for depositing more dimers (lattice is jammed). Initially I start with a lattice of zeroes, and the dimers are represented by a pair of \'1\'s. As

Auto increment in MongoDB to store sequence of Unique User ID

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问题 I am making a analytics system, the API call would provide a Unique User ID, but it\'s not in sequence and too sparse. I need to give each Unique User ID an auto increment id to mark a analytics datapoint in a bitarray/bitset. So the first user encounters would corresponding to the first bit of the bitarray, second user would be the second bit in the bitarray, etc. So is there a solid and fast way to generate incremental Unique User IDs in MongoDB? 回答1: You can, but you should not https://web

Does Python have a bitfield type?

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问题 I need a compact representation of an array of booleans, does Python have a builtin bitfield type or will I need to find an alternate solution? 回答1: Bitarray was the best answer I found, when I recently had a similar need. It's a C extension (so much faster than BitVector, which is pure python) and stores its data in an actual bitfield (so it's eight times more memory efficient than a numpy boolean array, which appears to use a byte per element.) 回答2: If you mainly want to be able to name