View source for Choice menu user input

[[Category:Analytica User Guide]]
<breadcrumbs>Analytica User Guide > Creating Interfaces for End Users > {{PAGENAME}}</breadcrumbs>


For the classes of nodes that can be used for parametric analysis, such as decision and variable, the '''''expr '''''menu includes the '''Choice '''option. The '''Choice '''option provides a way to offer the user a choice of selecting one or all values from a list.

'''Creating a menu from a list''': If the original variable is already defined as a list of numbers or labels, create a popup menu to select from the list as follows:

# Show the definition of the variable as a list, either in the ''Attribute ''view or the '''Object '''window.
# Click the '''''expr '''''menu and select the '''Choice '''option. Click '''OK '''to the question “''Replace current definition with a Choice?''” and click '''OK '''again to “''Replace current definition?''” when prompted. <br /> [[File:Chapter9 7.png]]
# The '''Object Finder '''dialog displays with parameter <code>I = Self</code> and <code>n = 1</code>. Click '''OK'''.

The definition field of the original variable now displays as a popup menu, and in browse mode, the input node displays as a popup menu. The original definition (list of numbers or labels) is now available as the '''''domain '''''of the variable — the possible outcomes. In the expression view, the popup menu displays as the [[Subscript and slice of a subarray|Choice() function]]

<tip title="Tip">To define ''Var1 ''as a popup menu of another variable ''Var2'', that is defined as a list, select '''Choice''' from the '''''expr '''''menu, and set the first parameter to <code>I = Var2</code> in the '''Object Finder '''dialog).</tip>

<tip title="Tip">To hide the '''All '''option on the popup, enter <code>inclAll = False</code> as the third parameter in the '''Object Finder '''dialog.</tip>

'''Creating a new definition''': If a variable has no previous definition, when you select '''Choice '''from the '''''expr '''''menu, a domain (possible outcomes) is created with a list of ''Explicit Values'', with one element in the list.

To change the domain to ''List of numbers'', press the '''Domain value type '''popup to the right of the '''Explicit Values '''pop-up and select '''Numbers'''.

'''Edit the list''' of values as you would edit a list of labels or list of numbers.

[[File:Chapter9_8.png]]

'''''Note: '''The values in the domain are evaluated deterministically.''

==See Also==
<footer>User Input nodes / {{PAGENAME}} / Checkbox user input</footer>