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Decision Optimization Visualization view

Visualization view

With the Decision Optimization experiment Visualization view, you can configure the graphical representation of input data and solutions for one or several scenarios.

The Visualization view is common to all scenarios in a Decision Optimization experiment.

For example, the following image shows the default bar chart that appears in the solution tab for the example that is used in the tutorial Solving and analyzing a model: the diet problem.

Visualization panel showing solution in table and bar chart

The Visualization view helps you compare different scenarios to validate models and business decisions.

For example, to show the two scenarios solved in this diet example tutorial, you can add another bar chart as follows:
  1. Click Chart and configure it by clicking the pencil icon.
  2. In the Chart Widget Editor, expand the Select scenario menu, and choose Scenario 1 (assuming that your current scenario is scenario 2), so that you have both scenario 1 and scenario 2 listed.
  3. In the Table field, select the Solution data option and select solution from the drop-down list.
  4. In the bar chart pane, select Descending for the Category order, Y-axis for the Bar type and click OK to close the Chart widget editor. A second bar chart is then displayed showing you the solution results for scenario 2.
  5. Re-edit the chart and select @Scenario in the Split by field of the Bar chart pane. You then obtain both scenarios in the same bar chart:

Chart with two scenarios displayed in one chart..

You can select many different types of charts in the Chart widget editor.

Alternatively using the Vega Chart widget, you can similarly choose Solution data>solution to display the same data, select value, and name in both the x and y fields in the Chart section of the Vega Chart widget editor. Then, in the Mark section, select @Scenario for the color field. This selection gives you the following bar chart with the two scenarios on the same y-axis, distinguished by different colors.

Vega chart showing 2 scenarios.

If you re-edit the chart and select @Scenario for the column facet, you obtain the two scenarios in separate charts side by side as follows:

Vega charts showing 2 scenarios side by side.

You can use many different types of charts that are available in the Mark field of the Vega Chart widget editor.

You can also select the JSON tab in all the widget editors and configure your charts by using the JSON code. A more advanced example of JSON code is provided in the Vega Chart widget specifications section.

The following widgets are available:

  • Notes widget

    Add simple text notes to the Visualization view.

  • Table widget

    Present input data and solution in tables, with a search and filtering feature. See Table search and filtering.

  • Charts widgets

    Present input data and solution in charts.

  • Gantt chart widget

    Display the solution to a scheduling problem (or any other type of suitable problem) in a Gantt chart.

    This widget is used automatically for scheduling problems that are modeled with the Modeling Assistant. You can edit this Gantt chart or create and configure new Gantt charts for any problem even for those models that don't use the Modeling Assistant.

Widget Editor

You can edit the widgets in the Widget Editor by clicking the Configure widget (pencil) icon in a widget. You can then customize it either in the Editor or by editing the JSON code.

In the Editor, you can easily change the name of your widget and select the source of the data you want to display in your Visualization view.

As you modify a widget in the Widget Editor, a preview is also displayed showing you your changes. You can then choose to save your changes by clicking OK, which closes the Widget Editor, or you can select Cancel to abandon your changes.

The JSON editor gives you more advanced editing possibilities. For more information about the JSON widget syntax, see the following section: Visualization widgets syntax.

You can download your Visualization view as a JSON file, containing the definitions and the data, making it easier for you to share your findings with your collaborators.

Visualization pages

You can create different pages for different scenarios or combine scenarios on the same page.

You can add pages by clicking the plus sign. You can then customize what is displayed on each page. You can also add pages in the Visualization Editor.

To edit a page, click the Edit (pencil) icon. In the Visualization Editor you can edit the page name, reorder, and add pages. You can also edit the page name by double-clicking the tab on the page.

To delete a page, click the delete button on the page tab or in the Visualization Editor.

Clicking OK in the Visualization Editor saves your updates and closes the editor. Or you can select Cancel to abandon your changes.

Table search and filtering

You can filter tables in the Prepare data, Explore solution and Visualization views, by clicking the search icon and entering a value to search on. You can also specify a column name, colon, and a value. For example, if you enter food:hot in the diet_food_nutrients table search field, the table is filtered to display only the rows that contain the food "hot". In this example, you obtain just one row that contains the food Hotdog. You can also enter the prefix of a column name. For example, entering fo:hot obtains the same result as food:hot. The column name is optional, so you can also enter hot in this case. If the column name is not specified, all columns are searched and the corresponding rows are obtained. For example, if you enter 0, in the diet_food_nutrients table you obtain four rows that contain this value in one of the columns. You can also filter by using numeric values as follows:

Enter in the search field Result: rows displayed containing column values
column_name:12 Equal to 12
column_name :10.. Greater than or equal to 10
column_name :..10 Less than or equal to 10
column_name:15..25 Between 15 and 25

Visualization widgets syntax

The widget syntax can be useful for customizing widgets beyond the functionality that is provided by the JSON editor.

The basic widget syntax is as follows:

{
  "name": "Widget Title",
  "type": "WidgetType",
  "props": {}
}
Table 1. Basic widget syntax
  Description

name

Defines the widget title, which is displayed in the widget header.

type

Defines the widget type.

props

Defines the properties of the widget. The properties vary depending on the type of widget.

The basic widget syntax for widgets that are connected to data, such as tables and charts, is as follows:

{
  "name": "Table Cars",
  "type": "Table",
  "props": {
    "container": "",
    "data": "cars",
    "spec": {},
    "search": ""
  }
}
Table 2. Basic syntax for widgets connected to data
  Description

data

You usually specify data. data refers to the table from which you want to extract data.

spec

You usually leave spec empty. The Visualization generates a default spec as a starting point.

container

Optionally specify container. If container equals "" or "$current-scenario", it references the current scenario. The latter is useful when you have multiple scenarios.

container can reference another scenario in the same Decision Optimization experiment by its name: "container":"Scenario 1". It can also reference a list of different scenarios: "container":["Scenario April","Scenario June"].

To aggregate all the scenarios contained in a Decision Optimization experiment, use "container":"*". container also supports the following syntax: "container":"/regex/" where all the scenarios with names that contain regex will be referenced. Add i after the forward slash to ignore case differences, for example "container":"/april/i" will reference all scenarios with names that contain april or April.

The rows of the listed scenarios are concatenated in a single table, with an extra column $scenario containing the name of the scenario.

search

Saves the content of the search-text field.

Notes widget specifications

The Notes widget can be styled as a post-it note, as shown in the following code sample:

{
  "name": "Notes",
  "type": "Notes",
  "props": {
    "notes": "My post-it note",
    "style": {
      "background": "#ffe"
    },
    "headerStyle": {
      "background": "#ffe"
    }
  }
}

This style example is applicable to other widgets.

Table widget specifications

Table widget specifications are composed of a list of columns that follow this syntax:

{
  "name": "Table Cars",
  "type": "Table",
  "property": "Acceleration",
  "label": "Acceleration",
  "type": "Number",
  "visible": true,
  "width": 100,
  "style": {}
}
Table 3. Table widget specifications
  Description

property

Key property to access data in the specified row.

type

Required to have a proper search and filter feature, as numbers are not searched like strings.

visible

Allows the display or hiding of any column without completely removing its definition.

label

Defines the column headings.

style

Allows tables to be styled by adding CSS properties in camel case. For example, if you want to specify the alignment of text in a table, use textAlign rather than text-align.

You can customize the rendering of tables by using the following elements:

Table 4. Table widget customization
  Description

numbered

Displays row numbers.

compact

Reduces row height.

columnExpand

Set columnExpand to true to expand column widths to fit into the widget.

columnShrink

Set columnShrink to true to shrink the column widths to fit into the widget.

The search and filtering feature is available in tables. To search content in a table, click the search icon search icon. You can limit your search to a specific column by adding a prefix to your search as follows: "column heading":"search", for example name:chevrolet. To search values that range from x to x, use 10..20. You can also search values greater than x, for example 10.., and values less than x, for example ..20. For more information about table filtering, see Table search and filtering.

Charts widgets

You can use two types of chart widgets: Vega Charts and Charts. Different types of charts are available when you open these Chart widget editors.

Vega Chart widget specifications

The Vega Chart widget uses Vega-Lite specifications to create different types of chart (bar charts, point charts, and so on). If you leave spec empty, a simple bar chart is automatically generated with the first string column in x-axis and the first number in y-axis.

Vega-Lite enables data filtering and transformation. For example, strings can be transformed into dates.

To learn more about Vega-Lite, see Vega-Lite - A High-Level Visualization Grammar.

The following is an advanced example of a grouped bar chart based on a population data table. This example shows how to filter data and how to compute a virtual column:

{
  "name": "Population Grouped Bar Chart",
  "type": "Chart",
  "props": {
    "data": "population",
    "spec": {
      "transform": [
        {
          "filter": "datum.year == 2000"
        },
        {
          "calculate": "datum.sex == 2 ? 'Female' : 'Male'",
          "as": "gender"
        }
      ],
      "mark": "bar",
      "encoding": {
        "column": {
          "field": "age",
          "type": "ordinal"
        },
        "y": {
          "aggregate": "sum",
          "field": "people",
          "type": "quantitative",
          "axis": {
            "title": "population",
            "grid": false
          }
        },
        "x": {
          "field": "gender",
          "type": "nominal",
          "scale": {
            "rangeStep": 12
          },
          "axis": {
            "title": ""
          }
        },
        "color": {
          "field": "gender",
          "type": "nominal",
          "scale": {
            "range": [
              "#EA98D2",
              "#659CCA"
            ]
          }
        }
      },
      "config": {
        "facet": {
          "cell": {
            "strokeWidth": 0
          }
        },
        "axis": {
          "domainWidth": 1
        }
      }
      }
    }
  }

Gantt chart widget

Gantt charts are automatically created to display the solution for scheduling problems created with the Modeling Assistant. You can, however, edit, create and configure Gantt charts for any data where it is meaningful, using the Gantt widget. You can use the Widget Editor to select the relevant scenario, and Resources, Activities, Reservations and Dates to be displayed. You can also use the JSON editor to configure Gantt charts, by clicking the pencil icon and selecting the JSON pane.

The Gantt chart automatically generated for the Modeling Assistant uses the following JSON code. The data field value $cognitive-gantt here dynamically enables the Gantt widget to connect to the Modeling Assistant solution. This dynamic loading can also imply that it might take a moment for the Gantt chart to appear.
{
  "name": "",
  "type": "Gantt",
  "props": {
    "container": "",
    "data": "$cognitive-gantt",
    "spec": {},
    "search": ""
  }
}
To define your own Gantt chart, you can use the Widget Editor or edit the JSON code and provide the names of 3 of your tables to define the resources, activities and reservations data, as follows:
  "data": [
    "resourcesTableName",
    "activitiesTableName",
    "reservationsTableName"
  ],
Also provide a spec section to define these tables, as follows. The parent fields are optional but all other fields are mandatory.
  "resources": {
    "data": "resourcesTableName",
    "id": "id",
    "parent": "parent",
    "name": "name"
  },
  "activities": {
    "data": "activitiesTableName",
    "id": "id",
    "name": "name",
    "start": "start",
    "end": "end",
    "parent": "parent"
  },
  "reservations": {
    "data": "reservationsTableName",
    "activity": "activity",
    "resource": "resource"
  },

Another mandatory field that you must also define in the specification is the dateFormat so that all the common date formats can get converted into real dates. Some common date formats are for example 'yyyy-MM-dd', 'yyyy-MM-dd HH:mm:ss', and so on. You can also use S for milliseconds for Epoch time, for example, "dateFormat": "S". The dateFormat must match the "start" and "end" fields of the "activity" table.

The error message No time window defined is displayed until you define the activity table, with start and end fields that use the specified dateFormat.

The following optional fields are also available:
  • resourceQuantity where you can configure the quantity column in the resources table to enable the Gantt chart to get the necessary information to populate a Load Resource Chart for you. You can set this column as follows: "resourceQuantity": "quantity"

  • You can also set the type of Gantt chart that you need: ActivityChart or ScheduleChart. You can set the type as follows:"type": "ActivityChart",. You can also omit this setting and the default is ScheduleChart. If you choose to have an ActivityChart, you must provide more information about the constraints table name and the mapping for this table:
      "constraints": {
        "data": "constraintsTableName",
        "from": "from",
        "to": "to",
        "type": "type"
      },
    The from and to values are the column names in your constraints table that define the order of precedence of tasks. The type values here correspond to the Gantt-chart library values 0 to 3:
    START_TO_START: 0,
    START_TO_END: 2,
    END_TO_END: 3,
    END_TO_START: 1,
    For example, if your to task starts after the end of your from task, select 1 as the type value.
ScheduleChart example
{
  "name": "",
  "type": "Gantt",
  "props": {
    "container": "",
    "data": [
      "resources",
      "activities",
      "reservations"
    ],
    "spec": {
      "resources": {
        "data": "resources",
        "id": "id",
        "parent": "parent",
        "name": "name"
      },
      "activities": {
        "data": "activities",
        "id": "id",
        "name": "name",
        "start": "start",
        "end": "end",
        "parent": "parent"
      },
      "reservations": {
        "data": "reservations",
        "activity": "activity",
        "resource": "resource"
      },
      "dateFormat": "S",
      "resourceQuantity": "quantity"
    },
    "search": ""
  }
}
ActivityChart example
{
  "name": "",
  "type": "Gantt",
  "props": {
    "container": "",
    "data": [
      "resources",
      "activities",
      "reservations",
      "constraints"
    ],
    "spec": {
      "type": "ActivityChart",
      "resources": {
        "data": "resources",
        "id": "id",
        "parent": "parent",
        "name": "name"
      },
      "activities": {
        "data": "activities",
        "id": "id",
        "name": "name",
        "start": "start",
        "end": "end",
        "parent": "parent"
      },
      "constraints": {
        "data": "constraints",
        "from": "from",
        "to": "to",
        "type": "type"
      },
      "reservations": {
        "data": "reservations",
        "activity": "activity",
        "resource": "resource"
      },
      "dateFormat": "S",
      "resourceQuantity": "quantity"
    },
    "search": ""
  }
}

Learn more

For other types of charts, see Visualizing your data.

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