markov alternatives and similar shards
Based on the "Algorithms and Data structures" category.
Alternatively, view markov alternatives based on common mentions on social networks and blogs.
4.1 0.4 markov VS kd_treeCrystal implementation of "K-Dimensional Tree" and "N-Nearest Neighbors"
4.0 0.4 markov VS haversineCrystal implementation of the Haversine formula to calculate distances between two points given their latitudes and longitudes
3.7 0.0 markov VS murmur3Crystal implementation of Murmur3 hash algorithm used by Cassandra
Do you think we are missing an alternative of markov or a related project?
A Crystal library for building Markov Chains and running Markov Processes.
What is a Markov Chain?
A Markov Chain is essentially a mechanism for guessing probable future events based on a sample of past events. For a great explanation, watch this Khan Academy video.
Visit the API Documentation for a more in-depth look at the library's functionality.
Add this to your application's
dependencies: markov: github: mccallofthewild/markov
In your terminal, install Crystal dependencies with:
$ shards install
$ crystal deps
Begin by requiring the
Basic -- Hello Markov
A classic Markov text generator. This example will work well for small (array-sized) data sets.
Markov::Chain is a generic type which contains, receives and generates elements of
We'll start with the sample text:
example_string = "how much wood would a woodchuck chuck if a woodchuck could chuck wood"
There are several
Markov::Chain constructors to choose from. The simplest one takes in a
LinkType array of elements as
sample and a
seed is the element in
sample you want to start the chain with. If not provided, a random element will be chosen.
example_arr = example_string.split(" ") #=> ["how","much","wood","would","a","woodchuck","chuck","if","a","woodchuck","could","chuck","wood"] seed = example_arr #=> "how" example_chain = Markov::Chain(String).new sample: example_arr, seed: seed
Finally, we'll generate a probable sequence of elements with the
["much", "wood", "would", "a", "woodchuck", "could", "chuck", "if", "a", "woodchuck"]
If we wanted to get the elements one at a time, we could use the
Markov::Chain#next method instead:
puts example_chain.next #=> "much" puts example_chain.next #=> "wood" puts example_chain.next #=> "would"
This implementation was built for larger data sets, with asynchronous input in mind.
In this example, we will create a
Markov::Chain which can generate realistic movie titles.
To begin, we instantiate a
TransitionTable is a mechanism for training and implementing Markov processes.
example_table = Markov::TransitionTable(String).new
Now we'll add a movie title using the
movie_one = %w(the great gatsby) # shortcut syntax for ["the","great","gatsby"] movie_one.each do |word| example_table.add(word) end
Markov::TransitionTable#add adds elements one at a time. At a deeper level, it's adding each new word to the previous word's Transition Matrix (
For syntactic sugar, if we have an array of elements, we can avoid looping through and
#add-ing them by using the
Markov::TransitionTable#fill method instead:
movie_one = %w(the great gatsby) # shortcut syntax for ["the","great","gatsby"] example_table.fill table_with: movie_one
A problem arises at this point:
movie_two = %w(great expectations) example_table.fill table_with: movie_two
The above code sequentially adds each word to the
TransitionTable. But The Great Gatsby and Great Expectations are two separate movie titles; the "Great" at the beginning of Great Expectations is not a probable transition from the "Gatsby" at the end of The Great Gatsby.
To solve this, use
#reset clears the
TransitionTable's last added key, allowing us to separate titles like so:
movie_one = %w(the great gatsby) example_table.fill table_with: movie_one example_table.reset movie_two = %w(great expectations) example_table.fill table_with: movie_two example_table.reset movie_three = %w(the great escape) example_table.fill table_with: movie_three
TransitionTable with a
Finally, we can put the
TransitionTable to use by passing it to a
Markov::Chain constructor as
example_chain = Markov::Chain(String).new transition_table: example_table, seed: "great"
Handling Dead Ends
With small and/or unique data sets, Markov chains are fallible to reaching dead ends. That is, they can often reach a point where there is nothing to transition to.
When this happens in the
Markov::Exceptions::EmptyTransitionMatrixException is raised.
dead_end_array = %w(some say the world will end in fire) dead_end_chain = Markov::Chain(String).new sample: dead_end_array, seed: "fire" # nothing comes after "fire", so the chain is at a dead end. dead_end_chain.next # raises `EmptyTransitionMatrixException`
To prevent this, use the
Markov::Chain#on_dead_end exception handler.
This method takes in a callback block with arguments of: the
Markov::Chain instance, and the
The block's return value of
LinkType fills in as the next item in the chain.
dead_end_array = %w(some say the world will end in fire) dead_end_chain = Markov::Chain(String).new sample: dead_end_array, seed: "fire" dead_end_chain.on_dead_end do |transition_table, chain, exception| "some" end dead_end_chain.next #=> "some" dead_end_chain.next #=> "say" dead_end_chain.next #=> "the"
- Fork it ( https://github.com/mccallofthewild/markov/fork )
- Create your feature branch (git checkout -b my-new-feature)
- Commit your changes (git commit -am 'Add some feature')
- Push to the branch (git push origin my-new-feature)
- Create a new Pull Request
- McCall Alexander mccallofthewild - creator, maintainer