PivotTable

This package provides a pivot table view function with which you can analyze and visualize your data by grouping various fields.

Definition

type Table row

In this package, a table is defined as a list of rows.

In the most naive case, a table may be represented by a list of records like:

type alias Person =
    { name : String
    , age : Int
    , gender : Gender
    }


type Gender
    = Male
    | Female


type alias MyTable =
    Table Person

Note: Notice that rows can be any type.

type alias Field row a =

row -> a

In this package, a field is defined as a function from row to something.

Table operations

makeTable : List row -> Table row

A function to create a table.

Since the Table is an opaque type, all user of this package must use this function to create a Table value.

getField : Field row a -> Table row -> List a

A function to get values from a table.

With the example appeared in the Table doc, each field can be accessed like:

nameField = .name
ageField = .age
genderField = .gender


myTable : MyTable
myTable = makeTable
    [ { name = "Alice",   age = 17, gender = Female }
    , { name = "Bob",     age = 8,  gender = Male   }
    , { name = "Charlie", age = 35, gender = Male   }
    ]


getField nameField myTable   -- ["Alice", "Bob", "Charlie"]
getField ageField myTable    -- [17, 8, 35]
getField genderField myTable -- [Female, Male, Male]

Note: Notice that a field does not have to be a record element. This is a valid code:

nameInitialLetterField = .name >> String.left 1


getField nameInitialLetterField myTable -- ["A", "B", "C"]

Pivot table

In this package, a pivot table is a table to show values grouped by some fields.

Example 1

genderToString : Gender -> String
genderToString gender =
    case gender of
        Male   -> "Male"
        Female -> "Female"


pivotTable
    { rowGroupFields = []
    , colGroupFields = [ genderField ]
    , aggregator = List.length
    , viewRow = always Element.none
    , viewCol = Element.text
    , viewAgg = String.fromInt >> Element.text
    }
    myTable

The code above produces a table:

|Male |Female |
|-----|-------|
|2    |1      |

type alias Aggregator row agg =

List row -> agg

The pivot table groups table rows. After that, the Aggregator aggregates the list of rows into a single value (of any type).

pivotTable :

{ rowGroupFields : List (Field row comparable1)

, colGroupFields : List (Field row comparable2)

, aggregator : Aggregator row agg

, viewRow : comparable1 -> Element msg

, viewCol : comparable2 -> Element msg

, viewAgg : agg -> Element msg

}

-> Table row

-> Element msg

Draws a pivot table.

rowGroupFields is a list of Field's to group and generates grouped rows.
colGroupFields is a list of Field's to group and generates grouped columns.
aggregator aggregates each grouped set of table data into a single value.
viewRow, viewCol and viewAgg are view functions to show each headers and cells.

pivotTableHtml :

{ rowGroupFields : List (Field row comparable1)

, colGroupFields : List (Field row comparable2)

, aggregator : Aggregator row agg

, viewRow : comparable1 -> Html msg

, viewCol : comparable2 -> Html msg

, viewAgg : agg -> Html msg

}

-> Table row

-> Html msg

Draws a pivot table of Html type.

This view makes use of colspan and rowspan attributes of html table. Use this view function when you want to avoid using elm-ui.

Modules

PivotTable