Histogram

Summary

The Histogram class creates histograms. Histograms visually summarize the distribution of one or more continuous numeric variables by measuring the frequency at which certain values appear in the dataset.

Learn more about histograms in ArcGIS Pro

Discussion

When creating this object, optional arguments for the class constructor must be specified using the argument name; they cannot be specified by argument position. See the Code sample section for an example of how to specify arguments using keywords.

Syntax

Histogram(x, {splitCategory}, {miniChartsPerRow}, {showPreviewChart}, {binCount}, {showMean}, {showMedian}, {showStandardDeviation}, {showComparisonDistribution}, {dataTransformationType}, {dataTransformationParameters}, {title}, {description}, {xTitle}, {yTitle}, {dataSource}, {displaySize}, {theme})

Name	Explanation	Data type
x	The field names for the x-axis variables. The field must be a single numeric field name or a list of numeric field names. For a raster layer, specify a band name.	String
splitCategory (Optional)	A categorical field that adds a separate series for each unique value in the field.	String
miniChartsPerRow (Optional)	The number of mini charts that will be shown per row.	Integer
showPreviewChart (Optional)	Specifies whether the preview chart will be displayed for grid charts. True—The preview chart will be displayed. False—The preview chart will not be displayed. The default value is False.	Boolean
binCount (Optional)	The number of bins that will be displayed in the histogram.	Integer
showMean (Optional)	Specifies whether the mean statistical line will be visible in the histogram. True—The mean line will be visible in the histogram. False—The mean line will not be visible in the histogram.	Boolean
showMedian (Optional)	Specifies whether the median statistical line will be visible in the histogram. True—The median line will be visible in the histogram. False—The median line will not be visible in the histogram.	Boolean
showStandardDeviation (Optional)	Specifies whether the standard deviation lines will be visible in the histogram. True—The standard deviation lines will be visible in the histogram. False—The standard deviation lines will not be visible in the histogram.	Boolean
showComparisonDistribution (Optional)	Specifies whether the normal distribution comparison line will be visible in the histogram. True—The comparison line will be visible in the histogram. False—The comparison line will not be visible in the histogram.	Boolean
dataTransformationType (Optional)	Specifies the data transformation type that will be applied. When multiple x-axis fields are defined, use a list of strings—in the same order as the `x` parameter—to specify a transformation for each field. none—No transformation will be applied. logarithmic—A logarithmic transformation will be applied. squareRoot—A square root transformation will be applied. inverse—An inverse transformation will be applied. boxCox—A Box-Cox transformation will be applied.	String
dataTransformationParameters (Optional)	The data transformation parameters for the boxCox transformation. This parameter accepts a two-item list in which the first item is the power parameter and the second item is the shift parameter. When multiple x-axis fields are defined, use a two-dimensional list—in the same order as the `x` parameter—in which each inner list corresponds to the transformation parameters for one field. In this case, specify `None` for list items that correspond to transformations that are not boxCox. `chart = arcpy.charts.Histogram( x=['POPULATION', 'POPULATION'], dataTransformationType=['inverse', 'boxCox'], dataTransformationParameters=[None, [2, 5000]] )`	List
title (Optional)	The title of the chart. The title text appears at the top of the chart view and is used as the label for the chart in the Contents pane.	String
description (Optional)	The description of the chart. The description text appears at the bottom of the chart view.	String
xTitle (Optional)	The title of the x-axis of the chart.	String
yTitle (Optional)	The title of the y-axis of the chart.	String
dataSource (Optional)	The data source of the chart. When a chart is exported using the `exportToSVG` method or displayed in ArcGIS Notebooks, the data source will be read and rendered on the chart. Valid data sources include the following: Paths to datasets, including local datasets, UNC paths, and service URLs Apache Arrow table objects `Layer` or `Table` objects	Object
displaySize (Optional)	The size of the chart when exported using the `exportToSVG` method or displayed in ArcGIS Notebooks. The value must be specified as a two-item list in which the first item is the width of the chart and the second item is the height of the chart.	List
theme (Optional)	Specifies the theme that will be applied to the chart. Light—The Light theme will be applied. Medium—The Medium theme will be applied. Dark—The Dark theme will be applied.	String

Properties

Name	Explanation	Data type
binCount (Read and Write)	The number of bins that will be displayed in the histogram.	Integer
color (Read and Write)	The colors that will be applied to each chart series. The value should be a list of hexadecimal string values. If this property is not set, the series colors will match symbology colors where applicable; otherwise, a standard color palette will be applied.	List
dataSource (Read and Write)	The data source of the chart. When a chart is exported using the `exportToSVG` method or displayed in an ArcGIS notebook, the data source will be read and rendered on the chart. Valid data sources include the following: Paths to datasets, including local datasets, UNC paths, and service URLs Apache Arrow table objects `Layer` or `Table` objects	Object
dataTransformationParameters (Read and Write)	The data transformation parameters for the boxCox transformation. This parameter accepts a two-item list in which the first item is the power parameter and the second item is the shift parameter. When multiple x-axis fields are defined, use a two-dimensional list—in the same order as the `x` parameter—in which each inner list corresponds to the transformation parameters for one field. In this case, specify `None` for list items that correspond to transformations that are not boxCox. `chart = arcpy.charts.Histogram( x=['POPULATION', 'POPULATION'], dataTransformationType=['inverse', 'boxCox'], dataTransformationParameters=[None, [2, 5000]] )`	List
dataTransformationType (Read and Write)	Specifies the data transformation type that will be applied. When multiple x-axis fields are defined, use a list of strings—in the same order as the `x` parameter—to specify a transformation for each field. none—No transformation will be applied. logarithmic—A logarithmic transformation will be applied. squareRoot—A square root transformation will be applied. inverse—An inverse transformation will be applied. boxCox—A box-cox transformation will be applied.	String
description (Read and Write)	The description of the chart. The description text appears at the bottom of the chart view.	String
displaySize (Read and Write)	The size of the chart when exported using the `exportToSVG` method or displayed in an ArcGIS notebook. The value must be specified as a two-item list in which the first item is the width of the chart and the second item is the height of the chart.	List
enableServerSideProcessing (Read and Write)	Specifies whether server-side processing will be used when data comes from an enterprise database or cloud data warehouse. True—Server-side processing will be enabled. False—Server-side processing will be disabled.	Boolean
legend (Read and Write)	The properties of the chart legend. `alignment`—Specifies the alignment of the legend. Alignment options are `left`, `bottom`, `top`, and `right`. `title`—The title of the legend. `visible`—Specifies whether the legend will be displayed in the chart view. `True` displays the legend, and `False` hides the legend.	Object
miniChartsPerRow (Read and Write)	The number of mini charts that will be shown per row.	Integer
showComparisonDistribution (Read and Write)	Specifies whether the normal distribution comparison line will be visible in the histogram. True—The comparison line will be visible in the histogram. False—The comparison line will not be not visible in the histogram.	Boolean
showMean (Read and Write)	Specifies whether the mean statistical line will be visible in the histogram. True—The mean line will be visible in the histogram. False—The mean line will not be visible in the histogram.	Boolean
showMedian (Read and Write)	Specifies whether the median statistical line will be visible in the histogram. True—The median line will be visible in the histogram. False—The median line will not be visible in the histogram.	Boolean
showPreviewChart (Read and Write)	Specifies whether the preview chart will be displayed for grid charts. True—The preview chart will be displayed. False—The preview chart will not be displayed.	Boolean
showStandardDeviation (Read and Write)	Specifies whether the standard deviation lines will be visible in the histogram. True—The standard deviation lines will be visible in the histogram. False—The standard deviation lines will not be visible in the histogram.	Boolean
splitCategory (Read and Write)	A categorical field that adds a separate series for each unique value in the field.	String
theme (Read and Write)	Specifies the theme that will be applied to the chart. Light—The Light theme will be applied. Medium—The Medium theme will be applied. Dark—The Dark theme will be applied.	String
title (Read and Write)	The title of the chart. The title text appears at the top of the chart view and is used as the label in the Contents pane on the List By Drawing Order tab .	String
type (Read only)	The string value indicating the chart type.	String
x (Read and Write)	The field names for the x-axis variables. The field must be a single numeric field name or a list of numeric field names. For a raster layer, specify a band name.	String
xAxis (Read and Write)	Specifies the properties of the x-axis. `addGuide`—Adds a guide to the axis using a `Guide` object. `field`—The field name for the x-axis variable. The field must be a numeric field. `listGuides`—A list of `Guide` objects for the axis. `logarithmic`—This property is not supported for the `Histogram` class. `maximum`—The maximum axis bound. `minimum`—The minimum axis bound. `removeGuide`—Removes the guide specified by the `Guide` object argument. `sort`—This property is not supported for the `Histogram` class. `title`—The label of the axis that displays on the chart. `useAdaptiveBounds`—Specifies whether a grid chart displays with adaptive or fixed axis bounds. `True` displays the axis with adaptive bounds. `False` displays the axis with fixed bounds.	Object
yAxis (Read and Write)	Specifies the properties of the y-axis. `addGuide`—Adds a guide to the axis using a `Guide` object. `field`—This property is not supported for the `Histogram` class. `listGuides`—A list of `Guide` objects for the axis. `logarithmic`—This property is not supported for the `Histogram` class. `maximum`—The maximum axis bound. `minimum`—The minimum axis bound. `removeGuide`—Removes the guide specified by the `Guide` object argument. `sort`—This property is not supported for the `Histogram` class. `title`—The label of the axis that displays on the chart. `useAdaptiveBounds`—Specifies whether a grid chart displays with adaptive or fixed axis bounds. `True` displays the axis with adaptive bounds. `False` displays the axis with fixed bounds.	Object

Methods

`addToLayer(layer_or_layerfile)`

The addToLayer method adds the chart object to a layer or table view.

Adding the chart object to a layer or table using the addToLayer method is often the final step after defining chart properties.

Name	Explanation	Data type
layer_or_layerfile	The chart will be added to the target object. This argument can be a `Layer` or `Table` object.	Object

Add a chart to an existing layer.

import arcpy

# Insert creation of chart object here
# ...

aprx = arcpy.mp.ArcGISProject("current")
map = aprx.listMaps()[0]
censusLayer = map.listLayers('Census Block Groups')[0]

# Add chart object to a layer
chart.addToLayer(censusLayer)

`exportToJPEG(path, width, height)`

The exportToJPEG method exports a chart to JPEG format.

The chart is exported to a .jpg file that can be shared and viewed outside of ArcGIS Pro. JPEG is a raster image format that uses lossy compression to reduce file size.

Name	Explanation	Data type
path	The path where the chart will be exported in JPEG format.	String
width	The width of the output graphic.	Integer
height	The height of the output graphic.	Integer

Export a chart that has a feature service data source to a .jpeg file.

import arcpy

# Insert creation of chart object here
# ...

featureServiceURL = r'https://services1.arcgis.com/hLJbHVT9ZrDIzK0I/arcgis/rest/services/CrimesChiTheft/FeatureServer/0'

# Set data source of chart object to a feature service URL
chart.dataSource = featureServiceURL

# Save the chart to file with dimensions width=800, height=600
chart.exportToJPEG('theftsPerBeat.jpg', 800, 600)

`exportToPNG(path, width, height)`

The exportToPNG method exports a chart to PNG format.

The chart is exported to a .png file that can be shared and viewed outside of ArcGIS Pro. PNG is a raster image format that uses lossless compression to preserve image quality.

Name	Explanation	Data type
path	The path where the chart will be exported in PNG format.	String
width	The width of the output graphic.	Integer
height	The height of the output graphic.	Integer

Access an existing chart from a layer, update the title, and export it to a .png file.

import arcpy

lyr = arcpy.mp.ArcGISProject('current').listLayers()[0]

# Retrieve the first chart belonging to the layer
chart = lyr.listCharts()[0]

# Update chart title
chart.title = 'Voter Turnout by State'

# Save the chart to PNG file with dimensions width=800, height=600
chart.exportToPNG('populationByState.png', 800, 600)

`exportToSVG(path, width, height)`

The exportToSVG method exports a chart to SVG format.

The chart is exported to an .svg file that can be shared and viewed outside of ArcGIS Pro. SVG is a vector image format that allows for editing and infinite scaling of the graphic without a loss in quality.

Name	Explanation	Data type
path	The path where the chart will be exported in SVG format.	String
width	The width of the output graphic.	Integer
height	The height of the output graphic.	Integer

Export a chart that has a project layer data source to an .svg file.

import arcpy

# Insert creation of chart object here
# ...

aprx = arcpy.mp.ArcGISProject('current')
censusLayer = aprx.listMaps()[0].listLayers('Census Block Groups')[0]

# Set data source of chart object to a layer in current project
chart.dataSource = censusLayer

# Save the chart to file with dimensions width=500, height=500
chart.exportToSVG('populationByState.svg', 500, 500)

`updateChart()`

The updateChart method updates chart properties to sync changes between the object and the chart previously added to a layer.

Adding the chart object to a layer using the addToLayer method is often the final step after defining chart properties.

You can also modify the properties of the original chart instead of starting with a new chart. You can then use the updateChart method to synchronize any changes into the chart that was added to the layer. This allows the changes you make to be presented in the Chart properties pane and chart view.

Use the updateChart method to synchronize chart property changes into a layer.

import arcpy

# Insert creation of chart object here
# ...

chart.addToLayer(myLayer)

# Further modification is necessary
chart.description = "Data from the U.S. Census Bureau"
chart.updateChart()

Code sample

Create a histogram using a layer name as the data source and export the histogram to an .svg file.

import arcpy

chart = arcpy.charts.Histogram("price", binCount=20, showMedian=True)
chart.dataSource = "airbnb_listings"
chart.title = "Distribution of AirBnB Listing Price"
chart.exportToSVG("histogram.svg", width=1000, height=800)