Type Alias ViewConfigUpdate

Aggregates perform a calculation over an entire column, and are displayed when one or more Group By are applied to the View. Aggregates can be specified by the user, or Perspective will use the following sensible default aggregates based on column type:

• "sum" for integer and float columns
• "count" for all other columns

Perspective provides a selection of aggregate functions that can be applied to columns in the View constructor using a dictionary of column name to aggregate function name.

The columns property specifies which columns should be included in the [crate::View]'s output. This allows users to show or hide a specific subset of columns, as well as control the order in which columns appear to the user. This is represented in Perspective as an array of string column names.

The expressions property specifies new columns in Perspective that are created using existing column values or arbitary scalar values defined within the expression. In <perspective-viewer>, expressions are added using the "New Column" button in the side panel.

The filter property specifies columns on which the query can be filtered, returning rows that pass the specified filter condition. This is analogous to the WHERE clause in SQL. There is no limit on the number of columns where filter is applied, but the resulting dataset is one that passes all the filter conditions, i.e. the filters are joined with an AND condition.

Perspective represents filter as an array of arrays, with the values of each inner array being a string column name, a string filter operator, and a filter operand in the type of the column.

A group by groups the dataset by the unique values of each column used as a group by - a close analogue in SQL to the GROUP BY statement. The underlying dataset is aggregated to show the values belonging to each group, and a total row is calculated for each group, showing the currently selected aggregated value (e.g. sum) of the column. Group by are useful for hierarchies, categorizing data and attributing values, i.e. showing the number of units sold based on State and City. In Perspective, group by are represented as an array of string column names to pivot, are applied in the order provided; For example, a group by of ["State", "City", "Postal Code"] shows the values for each Postal Code, which are grouped by City, which are in turn grouped by State.

The sort property specifies columns on which the query should be sorted, analogous to ORDER BY in SQL. A column can be sorted regardless of its data type, and sorts can be applied in ascending or descending order. Perspective represents sort as an array of arrays, with the values of each inner array being a string column name and a string sort direction. When column-pivots are applied, the additional sort directions "col asc" and "col desc" will determine the order of pivot columns groups.

A split by splits the dataset by the unique values of each column used as a split by. The underlying dataset is not aggregated, and a new column is created for each unique value of the split by. Each newly created column contains the parts of the dataset that correspond to the column header, i.e. a View that has ["State"] as its split by will have a new column for each state. In Perspective, Split By are represented as an array of string column names to pivot.