Tagged sequence | F# Snippets

Snippets tagged sequence

Largest Palindrome Number from Product of Two Three Digit Numbers

Here is an improved version twice shorter, than original
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Posted: 14 years ago by Nick Canzoneri
EnumerableStream

A lazy enumerable/stream of bytes.
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Posted: 13 years ago by Ryan Riley
Function to generate circular infinite sequence from a list

Function to generate circular infinite sequence from a list
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Posted: 13 years ago by Ankur Dhama
Gaussian Random Sequence

Normalized Random sequence generator conforming to the user supplied mean and sigma utilizing a "seed factory" instead of the default time of day. The Gaussian sequence is based on the central limit theory, averages together the flat distribution from the random generator built into .NET. Two examples of using normalRand are given to create infinite sequences of white and brown(ian) noise.
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Posted: 13 years ago by Tony Lee
Tree using sequences

Tree implementation using sequences.
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Posted: 13 years ago by Ankur Dhama
Select n elements in group from seq

Select n elements in group from seq
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Posted: 13 years ago by Ankur Dhama
Repeat until

Repeatedly call a function until it returns a positive result. Implemented using sequences.
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Posted: 13 years ago by Johann Deneux
ByteString

An initial attempt at creating a ByteString type based on the Haskell version.
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Posted: 13 years ago by Ryan Riley
Seq.reduceBallanced function

The function has the same type as Seq.reduce. Instead of reducing elements from the left to the right, it splits the input into two halves, reduces each half separately and then aggregates the results using the given function. This means that the values are aggregated into a ballanced tree, which can save stack space.
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Posted: 13 years ago by Tomas Petricek
Partition a list

The snippet implements 'List.partitionWhile' which behaves as a combination of 'Seq.takeWhile' and 'Seq.skipWhile': It splits the list into a part containing elements from the beginning of a list that match a given predicate and remaining elements.
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Posted: 12 years ago by Tomas Petricek
Primes

Generates the Prime Number Sequence.
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Posted: 12 years ago by AdamSpeight2008
Cartesian product in sequence expression

Sequence expression which deals with cartesian product of sequences with for ... do expression. It replaces nested for .. do expression to single one.
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Posted: 11 years ago by nagat01
Splitting a sequence based on separator condition

Whilst working on a google API wrapper, I came across the need to separate a sequence into sub-sequences based on a separator condition. This also led to a requirement for versions of takeWhile and skipWhile which also include the element which first breaks the condition predicate.
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Posted: 10 years ago by Chris Ballard
Treat a sequence as a circular sequence

Create a circular (repeating) sequence from an input sequence, optionally limiting the total number of elements.
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Posted: 9 years ago by Hugh Gleaves
Collapse a sequence

Eliminate repetitions in a sequence, preserving the first element in each run of repeats.
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Posted: 6 years ago by Kit Eason
Continue sequence after applying Seq.takeWhile, skip, take, etc

Sometimes you need to take more elements from a sequence, e.g. look at https://stackoverflow.com/questions/12562327/how-to-do-seq-takewhile-one-item-in-f This solution allows fetching elements from the same sequence after applying takeWhile, skip, take and other sequence functions. However, need to remember to call function with right parameter: use 'true' to include current element into result sequence (after takeWhile for example)
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Posted: 4 years ago by Ruslan Enikeev

Asynchronous sequences

An asynchronous sequence is similar to the seq type, but the elements of the sequence are generated asynchronously without blocking the caller as in Async. This snippet declares asynchronous sequence and uses it to compare two files in 1k blocks.
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Posted: 14 years ago by Tomas Petricek
Fibonacci sequence

Cached fib sequence
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Posted: 13 years ago by Dmitri Pavlenkov
Take every Nth element of sequence

A function that takes every Nth element of a sequence where N is passed as an argument. The snippet shows a naive function and a function using IEnumerator directly to provide an efficient implementation.
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Posted: 13 years ago by Tomas Petricek
Chronological sequence window beginnings

An abstraction of the following use case: Given a sequence of dates and max temperatures for each date, extract out the initial dates on which the temp is greater than a given threshold for n consecutive days. (Originally posted as an answer to this StackOverflow question: http://stackoverflow.com/questions/5267055 )
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Posted: 13 years ago by ildjarn
exec with redirected io as sequences

Since F# is my new scripting language, I needed something like Perl's exec but with sequences for Std In and Out.
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Posted: 13 years ago by Tony Lee
Incremental (Functional) QuickSort

Functional quicksort inspired by the Haskell Quick Sort at http://www.haskell.org/haskellwiki/Introduction. Since F# lists aren't lazy, uses sequences instead of lists to be haskell like. Roughly O(n) if you Seq.take 1, full on QS if you enumerate the whole thing.
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Posted: 13 years ago by Tony Lee
Seq group continuous matching elements

Seq group continuous matching elements [1;1;1;2;2;2] will become [ [1;1;1] ; [2;2;2] ]
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Posted: 13 years ago by Ankur Dhama
Splice sequence into other sequence

Splices a sequence into another sequence at a specified index n. Can replace the existing element at n or keep it.
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Posted: 13 years ago by Henrik Ravn
Nest items of a sequence

A function that nests items of a sequence that do not match a specified predicate under the last item that matches the predicate. The input is a sequence of values and the result is a sequence of pairs where the second element is a list of nested items.
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Posted: 12 years ago by Tomas Petricek
Enumerable extraction in query expressions

Adds "enumerable extraction" support to query expressions
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Posted: 12 years ago by kvb
The Dominator of Array

The dominator of array A is the value that occurs in more than half of the elements of A. It is a zero-indexed based array consisting of N integers (A [] with N length). To find the index array of the dominator from a A [], we can use a helpful function from Seq module call 'Seq.groupBy' to mitigate the implementation of a solution.
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Posted: 12 years ago by Joel Huang
Convert list of sequences to sequence of lists

Function to combine the values of a list of sequences into a sequence of lists where each list contains the nth element of the different sequences. It works like zip but for an arbitrary number of sequences and it returns lists instead of tuples. As with zip when one sequence is exhausted any remaining elements in the other sequences are ignored.
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Posted: 11 years ago by Samuel Bosch
Decoder for Google API polylines

Full source code for my blog entry on this subject - http://chrsb.co/BNqAbM
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Posted: 10 years ago by Chris Ballard
Sequence Random Permutation

A generic function that randomly permutes the elements of a sequence.
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Posted: 7 years ago by Taha Hachana
Exponentiation by squaring

Function, what calculates x^n by non-recursive basic exponentiation squaring algorithm. This method uses the bits of the exponent to determine computing powers. Generic parameter x suitable for any type what supports multiplication. I do not suppose existence of inverse operator like "/", thus parameter n must be a positive integer only. It is not difficult to define an extended variant for a type what supports division.
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Posted: 4 years ago by Pavel Tatarintsev
groupAdjacent

A variation of another snippet "Seq.groupWhen". This one groups adjacent elements based on a predicate that accepts two arguments - the previous and current elements
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Posted: 1 year ago by Faisal Waris