Numeric visualizations (color & size)
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Numeric visualizations use a numeric attribute to either vary colors or sizes between ranges of values and are defined in FSL with "type: numeric".
Ranges are calculated between 3-10 discrete steps using a classification method or on a continuous scale between an attribute’s min and max values. Felt offers the following methods to symbolize numeric data:
Jenks Natural Breaks
Finds natural groupings in attribute values to minimize differences within steps and maximize differences between them. A good option for clustered data. This is the default method in Felt.
Equal interval
Divides attribute values into an equal number of steps. Equal interval is a good option when data is equally spread across the range of values.
Quantiles
Places an equal number of values into each step. A good option for evenly distributed data.
Mean Standard Deviation
Steps are calculated based on an attribute values distance from the mean. A good option for data that follows a near-normal distribution.
Manual
Manually define which values to include in each size or color step. A good option when you know your data well.
Continuous
Attribute values are sized or colored based on a continuous scale between the min and max values versus discrete steps. A good option for continuous data.
Color numeric values in your data using the color property.
Stepped color
This map shows the percent of renter occupied housing units by US county. Each county is colored according to the step of ranges it falls into using a sequential color palette where light colors are assigned to low values and darker colors for high values.
The style for this map is defined
with the visualization type: numeric
numericAttribute: "Renter occupied (%)" and the computed steps using Jenks Natural Breaks over 5 classes
the sequential color array where each color is applied to a distinct step range
Continuous Color
The map below shows average accumulated precipitation in the State of California between the years 1900 - 1960 and is colored along a continuous range between the min and max of the precipitation values.
In this case, the numeric style is applied using a continuous method.
In the config block, the numericAttribute: PRECIP has steps that range between the min and max values of [2.5,125]
The color property has an array of three colors ["#fde89b", "#f37b8a", "#4d53b3"] that are interpolated to give each precipitation value a unique color
Felt also supports stepped and continuous color numeric visualizations on raster datasets like you can see on the map below
which includes a raster layer with the following style
Notice that in the config block we are using band instead of numericAttribute to define which band will be used for display
Size numeric values in your point or line data using the size property.
Stepped size
The map below shows earthquakes over the past year sized with 5 manually defined steps.
In this case, the numeric style is applied using a classed method.
In the config block, the numericAttribute: mag has manually-defined steps for 5 classes
The size property has an array of five sizes, one for each defined class
Map link: Earthquakes Stepped Size
Continuous size
The map below shows tonnes of corn that have been exported from Ukraine since August 2022 under the UN’s Black Sea Grain Initiative. The symbol size for each country is proportionate to its value in the data.
To do this the min and max steps from the numericAttribute: tonnes are interpolated to be proportionately sized between a min and max point size — size:[5,48]
