Frames.Melt

Documentation

type family Elem t ts :: Bool

Equations

Elem t [] = False

Elem t (t : ts) = True

Elem t (s : ts) = Elem t ts

type family Or a b :: Bool

Equations

Or True b = True

Or a b = b

type family Not a :: Bool

Equations

Not True = False

Not False = True

type family Disjoint ss ts :: Bool

Equations

Disjoint [] ts = True

Disjoint (s : ss) ts = Or (Not (Elem s ts)) (Disjoint ss ts)

type ElemOf ts r = RElem r ts (RIndex r ts)

class RowToColumn ts rs where

Methods

rowToColumnAux :: Proxy ts -> Rec f rs -> [CoRec f ts]

Instances

RowToColumn ts ([] *)

((∈) * r ts, RowToColumn ts rs) => RowToColumn ts ((:) * r rs)

rowToColumn :: RowToColumn ts ts => Rec f ts -> [CoRec f ts]

Transform a record into a list of its fields, retaining proof that each field is part of the whole.

meltAux :: forall vs ss ts. (vs ⊆ ts, ss ⊆ ts, Disjoint ss ts ~ True, ts ≅ (vs ++ ss), ColumnHeaders vs, RowToColumn vs vs) => Record ts -> [Record (("value" :-> CoRec Identity vs) : ss)]

type family RDeleteAll ss ts

Equations

RDeleteAll [] ts = ts

RDeleteAll (s : ss) ts = RDeleteAll ss (RDelete s ts)

meltRow' :: forall proxy vs ts ss. (vs ⊆ ts, ss ⊆ ts, vs ~ RDeleteAll ss ts, Disjoint ss ts ~ True, ts ≅ (vs ++ ss), ColumnHeaders vs, RowToColumn vs vs) => proxy ss -> Record ts -> [Record (("value" :-> CoRec Identity vs) : ss)]

This is melt, but the variables are at the front of the record, which reads a bit odd.

retroSnoc :: forall t ts. Record (t : ts) -> Record (ts ++ `[t]`)

Turn a cons into a snoc after the fact.

meltRow :: (vs ⊆ ts, ss ⊆ ts, vs ~ RDeleteAll ss ts, Disjoint ss ts ~ True, ts ≅ (vs ++ ss), ColumnHeaders vs, RowToColumn vs vs) => proxy ss -> Record ts -> [Record (ss ++ `["value" :-> CoRec Identity vs]`)]

Like melt in the reshape2 package for the R language. It stacks multiple columns into a single column over multiple rows. Takes a specification of the id columns that remain unchanged. The remaining columns will be stacked.

Suppose we have a record, r :: Record [Name,Age,Weight]. If we apply melt [pr1|Name|] r, we get two values with type Record [Name, "value" :-> CoRec Identity [Age,Weight]]. The first will contain Age in the value column, and the second will contain Weight in the value column.

class HasLength ts where

Methods

hasLength :: proxy ts -> Int

Instances

HasLength k ([] k)

HasLength k ts => HasLength k ((:) k t ts)

melt :: forall vs ts ss proxy. (vs ⊆ ts, ss ⊆ ts, vs ~ RDeleteAll ss ts, HasLength vs, Disjoint ss ts ~ True, ts ≅ (vs ++ ss), ColumnHeaders vs, RowToColumn vs vs) => proxy ss -> FrameRec ts -> FrameRec (ss ++ `["value" :-> CoRec Identity vs]`)

Applies meltRow to each row of a FrameRec.