CaseBi

Function that can be used instead of

getBFst'

Arguments

:: Ord a

=> b

a default value that can be substituted if there is no correspendence in the set of (a, b) tuples (the otherwise or irrefutable pattern analogue)

-> Vector (a, b)

Vector of the (a, b) tuples that are sorted in ascending order for the first argument. If there are several pairs (a, b) with the same a, the function acts as if there is only the first one

-> a

an element for which the corresponding resulting b must be found

-> b

the result

The function that can be used instead of the 'case ... of' function

case var of
  a1 -> b1
  a2 -> b2
  a3 -> b3
  ...
  an -> bn
  _  -> defaultValue

The function 'case a of ...' gives the O(n) coplexity of the transformation of a to b here, but the function getBFst' tries to give about O(log n) complexity The Vector v (a, b) must be sorted in ascending order here for the algorithm to be used correctly. For this you can use the following functions sortFst and sortFstV.

b after Vector (a, b) in the type definition of the getBFst must be a defaultValue for case above.

Vector (a, b) corresponds to

 a1 -> b1
 a2 -> b2
 a3 -> b3
 ...
 an -> bn

getBFst

Arguments

:: Ord a

=> Vector (a, b)

Vector of the (a, b) tuples that are sorted in ascending order for the first argument

-> b

a default value that can be substituted if there is no correspendence in the set of (a, b) tuples (the otherwise or irrefutable pattern analogue)

-> [a]

a list of values needed to be transformed accordingly to the correct (a, b) tuple pairs

-> [b]

the resulting list

The function that uses special kind of bisection to effectively transform the [a] to [b] with instead of simply use

case var of
  a1 -> b1
  a2 -> b2
  a3 -> b3
  ...
  an -> bn
  _  -> defaultValue

The function 'map (f (case var of ...)) [a]' gives the O(n*m) coplexity of the transformation of [a] to [b] here where m is the length of the [a] (and [b] respectively here), but the function getBFst tries to give about O(m*log n) complexity The Vector (a, b) must be sorted in ascending order here for the algorithm to be used correctly. For this you can use the following functions sortFst and sortFstV. If m >> n than the function gives more efficiency. Even otherwise, it can be used to simplify the procedure for optimizing the code for transformation of the list data.

b after Vector (a, b) in the type definition of the getBFst must be a defaultValue for case above.

Vector (a, b) corresponds to

 a1 -> b1
 a2 -> b2
 a3 -> b3
 ...
 an -> bn

getBFstV

Arguments

:: Ord a

=> Vector (a, b)

Vector of the (a, b) tuples that are sorted in ascending order for the first argument

-> b

a default value that can be substituted if there is no correspendence in the set of (a, b) tuples (the otherwise or irrefutable pattern analogue)

-> Vector a

a Vector needed to be transformed accordingly to the correct (a, b) tuple pairs

-> Vector b

the resulting Vector

The function that uses special kind of bisection to effectively transform the Vector a to Vector b with instead of simply use

case var of
  a1 -> b1
  a2 -> b2
  a3 -> b3
  ...
  an -> bn
  _  -> defaultValue

The function 'V.map (f (case var of ...)) [a]' gives the O(n*m) coplexity of the transformation of Vector a to Vector b here where m is the length of the Vector a (and Vector b respectively here), but the function getBFstV tries to give about O(m*log n) complexity The Vector (a, b) must be sorted in ascending order here for the algorithm to be used correctly. For this you can use the following functions sortFst and sortFstV. If m >> n than the function gives more efficiency. Even otherwise, it can be used to simplify the procedure for optimizing the code for transformation of the Vector data.

b after Vector (a, b) in the type definition of the getBFstV must be a defaultValue for case above.

Vector (a, b) corresponds to

 a1 -> b1
 a2 -> b2
 a3 -> b3
 ...
 an -> bn

Additional functions that are used to sort a list of pairs (which can be obtained by e. g. Prelude.zip

sortFst :: Ord a => [(a, b)] -> [(a, b)]

Function that sorts a list of (a, b) tuples by the first argument (|a| must be an instance of class Ord) and is inspired by Data.List.sort function (the last one can be used for sorting the (a, b) tuples where both the types of a and b have instances of the class Ord).

sortFstV :: Ord a => [(a, b)] -> Vector (a, b)

Function that prepares the list of (a, b) tuples representing the

case var of 
  a1 -> b1
  a2 -> b2
  a3 -> b3
   ...
  an -> bn
  _  -> defaultValue

for usage in the getBFst and getBFstV functions. |a| must be an instance of class Ord.

Function that can be used for changing the Vector (a, b) during its creation

filterP

Arguments

:: Ord a

=> ((a, b) -> Bool)

The predicate p used to select the only one value of b in the pairs (a, b) with the same a. ^ If there are several pairs (a, b) for the same a that satisfies a predicate then the first one is used. For large [(a, b)] ^ it can be rather complex.

-> [(a, b)]

The list of (a, b) sorted in the ascending order by the first element a (e. g. by the sortFst function)

-> Vector (a, b)

The resulting filtered Vector (a, b) that can be used for getFstB' and its successor functions

Example:

filterP (\(t, w) -> (t == "1") || (w > 'f')) . sortFst $ [("1",'a'),("4a",'k'),("4a",'b'),("4a",'c'),("4a",'d'),("4a",'e'),("b7",'c'),("b7",'k')] = [("1",'a'),("4a",'k'),("b7",'k')]

The function that is used to filter a list [(a, b)] of the corresponding values for getFstB' to obtain the Vector (a, b) such that the b element for the sequence of pairs (a, b) with the same a is selected by the predicate p and is not necessarily the first one as it is for the getFstB' function and its successors by default.