CARTO for React

CARTO for React

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Core

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Set of common functions, to be used mostly by other packages. You won’t usually consume this package directly, but when using AggregationTypes for widgets or when creating custom widgets.

Tip: The computations performed internally by widgets use these functions. They can be useful in the context of new custom widgets (for example using a different charting library)

Functions

aggregationFunctions

Contains a set of basic aggregation functions (count, min, max, sum and average), used automatically for widgets and layers, see AggregationTypes. Functions are applicable to numbers and also objects using a numeric property

  • Input:
Param Type Description
values Array Array of numbers or objects with a numerical property
[key] string (optional). When using objects, name of the property to use for calculations

  • Returns: Object - An object with Aggregation functions, which keys are every AggregationTypes values

  • Example:

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    import { aggregationFunctions, AggregationTypes } from "@carto/react-core";

const values = [{ f: 1 }, { f: 2 }, { f: 3 }, { f: 4 }, { f: 5 }];
const avgFn = aggregationFunctions[AggregationTypes.AVG];

console.log(avgFn(values, "f")); // 3

groupValuesByColumn

Makes groups from f∫eatures based in a column (keysColumn) and applying an operation to the numeric values in a predefined column (valuesColumn).

  • Input:
Param Type Default Description
data Array Features for calculations (plain objects with properties)
valuesColumn string Quantitative column for grouping (the name of a numeric property in the object)
keysColumn string Qualitative column for grouping (the name of a string property in the object)
operation string Operation for groups calculations, see AggregationTypes

  • Returns: Array - Grouped values

  • Example:

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    import { groupValuesByColumn, AggregationTypes } from "@carto/react-core";

const data = [
  { category: "A", population: 100 },
  { category: "A", population: 200 },
  { category: "B", population: 50 },
];

const groups = groupValuesByColumn(data, "population", "category", AggregationTypes.SUM);

console.log(groups); // output: [ { name: 'A', value: 300 }, { name: 'B', value: 50 }]

histogram

Categorizes numeric values as a histogram from a set of features, having the option of just calculating the frequency (with COUNT operation) or an aggregated operation on the features inside the bin (eg. SUM).

  • Input:
Param Type Description
features Array Features for calculations (plain objects with properties)
columnName string Quantitative column for calculations (the name of a number property in the object)
ticks Array Array of numbers to build intervals (eg 1, 5, 10 will defines 4 intervals: <1, 1 to 5, 5 to 10 and >10)
operation string Operation for groups calculations, see AggregationTypes

  • Returns: Array - Histogram data for each bin, derived from ticks

  • Example:

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    import { histogram, AggregationTypes } from "@carto/react-core";

const features = [
  { field: 1 },
  { field: 2 },
  { field: 2 },
  { field: 3 },
  { field: 3 },
  { field: 3 },
  { field: 4 },
  { field: 4 },
  { field: 5 },
];

const ticks = [2, 4, 6];

const h = histogram(features, "field", ticks, AggregationTypes.COUNT);
console.log(h); // [1, 5, 3, 0]
/* 
        histogram results as:
        <2          --> 1 item
        >=2 to <4   --> 5 items
        >=4 to <6   --> 3 items
        >=6         --> 0 items
    */

Constants & enums

AggregationTypes

Enum for the different types of aggregations, available for widgets

  • Options:

    • COUNT
    • SUM
    • AVG
    • MIN
    • MAX

  • Example:

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    import { AggregationTypes } from "@carto/react-core";

console.log(AggregationTypes.COUNT);