sparsepp v1.22


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'Rcpp' Interface to 'sparsepp'

Provides interface to 'sparsepp' - fast, memory efficient hash map. It is derived from Google's excellent 'sparsehash' implementation. We believe 'sparsepp' provides an unparalleled combination of performance and memory usage, and will outperform your compiler's unordered_map on both counts. Only Google's 'dense_hash_map' is consistently faster, at the cost of much greater memory usage (especially when the final size of the map is not known in advance).


CRAN_Status_Badge License


Check original sparsepp repository and write-up which compares hashmap implementations.


Use sparsepp from another package

To use C++ code from sparsepp:

  1. In DESCRIPTION, add LinkingTo: sparsepp.
  2. In the C++ file, add: #include <sparsepp/spp.h>

Simple example

#include <sparsepp/spp.h>
using spp::sparse_hash_map;
sparse_hash_map<string, int> smap;

Defining custom hash function

#include <iostream>
#include <functional>
#include <string>
#include <sparsepp/spp.h>

using std::string;

struct Person 
    bool operator==(const Person &o) const 
    { return _first == o._first && _last == o._last; }

    string _first;
    string _last;

namespace std
    // inject specialization of std::hash for Person into namespace std
    // ----------------------------------------------------------------
    struct hash<Person>
        std::size_t operator()(Person const &p) const
            std::size_t seed = 0;
            spp::hash_combine(seed, p._first);
            spp::hash_combine(seed, p._last);
            return seed;

int main()
    // As we have defined a specialization of std::hash() for Person, 
    // we can now create sparse_hash_set or sparse_hash_map of Persons
    // ----------------------------------------------------------------
    spp::sparse_hash_set<Person> persons = { { "John", "Galt" }, 
                                             { "Jane", "Doe" } };
    for (auto& p: persons)
        std::cout << p._first << ' ' << p._last << '\n';

Functions in sparsepp

Name Description
sparsepp-package sparsepp
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Type Package
Date 2018-09-19
License BSD_3_clause + file LICENSE
Encoding UTF-8
RoxygenNote 6.0.1
NeedsCompilation no
Packaged 2018-09-22 16:08:38 UTC; dmitry
Repository CRAN
Date/Publication 2018-09-22 16:30:03 UTC
suggests Rcpp
Contributors Gregory Popovitch, Google Inc

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