### 2 unstable releases

0.2.0 | Jan 8, 2023 |
---|---|

0.1.0 | Dec 28, 2022 |

#**2315** in Data structures

Used in stromatekt

**MIT/Apache**

50KB

1.5K
SLoC

# Flat Multimap

A multimap and multiset implementation using a flattened hash table

###
`lib.rs`

:

A multimap and multiset implementation using a flattened hash table.

is a multimap
implementation where entries are stored as a flattened hash map:`FlatMultimap`

`a``->``1``a``->``2``b``->``3`

as opposed to the common implementation using a hash map which maps keys to a collection of values:

`a``->``1``,``2``b``->``3`

is a multiset
implementation where items are stored as a flattened hash set:`FlatMultiset`

`a``a``b`

as opposed to the common implementation using a hash map which maps items to a variable counting the number of occurances:

`a``->``2``b``->``1`

Storing elements as a flattened hash table * can* have the benefit
that it saves space compared to the common implementations.
This

*be the case when there are very few duplicates and/or the size of the elements is very small.*

**can**Disadvantages of storing elements this way compared to the common implementations is that much more space is required when there are many duplicates. Furthermore, there are no efficient operations which can get all the values associated with a single key (in the case of a map), and no efficient operations to count the number of duplicates.

#### Dependencies

~1.4–2MB

~30K SLoC