QQPlot

Summary

The QQPlot class creates QQ plots. Quantile-quantile (QQ) plots are an exploratory tool used to assess the similarity between the distribution of one numeric variable and a normal distribution, or between the distributions of two numeric variables.

Learn more about QQ plots 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

QQPlot(x, {y}, {showReferenceLine}, {dataTransformationType}, {dataTransformationParameters}, {title}, {description}, {xTitle}, {yTitle}, {dataSource}, {displaySize}, {theme})

Name	Explanation	Data type
x	The field name for the x-axis variable. The field must be a numeric field.	String
y (Optional)	The field name for the y-axis variable, which is used to compare against the distribution of the x-axis variable. The field must be a numeric field.	String
showReferenceLine (Optional)	Indicates whether the reference line is visible in the QQ plot. True—Displays the reference line. False—Hides the reference line.	Boolean
dataTransformationType (Optional)	The data transformation type. none—No transformation is applied. logarithmic—A logarithmic transformation is applied. squareRoot—A square root transformation is applied. inverse—An inverse transformation is applied. boxCox—A Box-Cox transformation is applied.	String
dataTransformationParameters (Optional)	The data transformation parameters for the Box-Cox transformation. This parameter accepts a two-item list where the first item is the power parameter and the second item is the shift parameter.	List
title (Optional)	Sets 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)	Sets 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	List
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
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 Box-Cox 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.	List
dataTransformationType (Read and Write)	Specifies the data transformation type. 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
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
showReferenceLine (Read and Write)	Specifies whether the reference line will be shown in the QQ plot. True—The reference line will be shown. False—The reference line will not be shown.	Boolean
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 name for the x-axis variable. The field must be a numeric field.	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. logarithmic—This property is not supported for the QQPlot class. listGuides—Returns a list of Guide objects for the axis. 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 QQPlot class. title—The label of the axis that displays on the chart.	Object
y (Read and Write)	The field name for the y-axis variable, which is used to compare to the distribution of the x-axis variable. The field must be a numeric field.	String
yAxis (Read and Write)	Specifies the properties of the y-axis. addGuide—Adds a guide to the axis using a Guide object. field—The field name for the y-axis variable, which is used to compare to the distribution of the x-axis variable. The field must be a numeric field. logarithmic—This property is not supported for the QQPlot class. listGuides—A list of Guide objects for the axis. 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 QQPlot class. title—The label of the axis that displays on the chart.	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 QQ plot using a layer name as the data source and export the plot to an .svg file.

import arcpy
chart = arcpy.charts.QQPlot(x="p_matter", dataTransformationType="squareRoot",
                            title="Comparison of Particular Matter and Normal Distribution",
                            dataSource="air_quality")
chart.exportToSVG("qqplot.svg", width=900, height=500)