QQPlot

Synthèse

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

Syntaxe

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

The field name for the x-axis variable. The field must be a numeric field.

String
y

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

Indicates whether the reference line is visible in the QQ plot.

  • TrueDisplays the reference line.
  • FalseHides the reference line.
Boolean
dataTransformationType

The data transformation type.

  • noneNo transformation is applied.
  • logarithmicA logarithmic transformation is applied.
  • squareRootA square root transformation is applied.
  • inverseAn inverse transformation is applied.
  • boxCoxA box-cox transformation is applied.
String
dataTransformationParameters

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

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

Sets the description of the chart. The description text appears at the bottom of the chart view.

String
xTitle

The title of the x-axis of the chart.

String
yTitle

The title of the y-axis of the chart.

String
dataSource

Sets the data source of the chart. When a chart is exported using the exportToSVG method or displayed in an ArcGIS Notebook, the data source is read and rendered on the chart. Valid data sources include paths to datasets, including local datasets, UNC paths, and service URLs, and arcpy.mp Layer objects.

Object
displaySize
[displaySize,...]

Sets the size of the chart when exported or displayed in an ArcGIS Notebook.

List

Propriétés

PropriétéExplicationType de données
dataSource
(Lecture et écriture)

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
  • Arrow table objects
  • Layer objects.

Object
dataTransformationParameters
(Lecture et écriture)

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
dataTransformationType
(Lecture et écriture)

The data transformation type.

  • noneNo transformation is applied.
  • logarithmicA logarithmic transformation is applied.
  • squareRootA square root transformation is applied.
  • inverseAn inverse transformation is applied.
  • boxCoxA box-cox transformation is applied.
String
description
(Lecture et écriture)

The description of the chart. The description text appears at the bottom of the chart view.

String
displaySize
(Lecture et écriture)

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
(Lecture et écriture)

The properties of the chart legend.

  • visible—Specifies whether the legend will be displayed in the chart view. True displays the legend, and False hides the legend.
  • title—The title of the legend.
Object
showReferenceLine
(Lecture et écriture)

Indicates whether the reference line is visible in the QQ plot.

  • TrueDisplays the reference line.
  • FalseHides the reference line.
Boolean
theme
(Lecture et écriture)

Specifies the name of the theme that is applied to the chart.

String
title
(Lecture et écriture)

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 Répertorier par ordre d'affichage.

String
type
(Lecture seule)

The string value indicating the chart type.

String
x
(Lecture et écriture)

The field name for the x-axis variable. The field must be a numeric field.

String
xAxis
(Lecture et écriture)

Sets the properties of the x-axis.

  • 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.
  • maximum—The maximum axis bound.
  • minimum—The minimum axis bound.
  • sort—This property is not supported for the QQPlot class.
  • title—The label of the axis that displays on the chart.
Object
y
(Lecture et écriture)

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
yAxis
(Lecture et écriture)

Sets the properties of the y-axis.

  • field—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.
  • logarithmic—This property is not supported for the QQPlot class.
  • maximum—The maximum axis bound.
  • minimum—The minimum axis bound.
  • sort—This property is not supported for the QQPlot class.
  • title—The label of the axis that displays on the chart.
Object

Vue d’ensemble des méthodes

MéthodeExplication
addToLayer (layer_or_layerfile)

Adds the chart object to a layer or stand-alone table.

exportToSVG (path, width, height)

Exports the chart to SVG format.

updateChart ()

Updates chart properties to sync changes between the object and the chart previously added to a layer.

Méthodes

addToLayer (layer_or_layerfile)
ParamètreExplicationType de données
layer_or_layerfile

The chart will be added to the target object. The layer_or_layerfile argument can be a Layer or a Table object.

Object

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

Add a chart to an existing layer.

import arcpy

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)
exportToSVG (path, width, height)
ParamètreExplicationType de données
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

In some cases, you may want to save the chart as a graphic that can be shared and viewed outside of ArcGIS Pro. Exporting to the SVG graphic format is beneficial, as the chart elements and text are stored as vector elements that can be independently modified in a vector graphics software. An SVG graphic can also be resized to any scale without pixelation or loss in quality.

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

import arcpy

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

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

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

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


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.exportToSVG('theftsPerBeat.svg', 800, 600)
updateChart ()

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

To further modify the chart properties, you can modify the properties of the original chart instead of starting from scratch 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 will allow 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.


chart.addToLayer(myLayer)

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

Exemple de code

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)