(Up to Analytica Graph Settings)
The Bar Origin graphing role controls the position of the origin end of a bar in a bar graph. Control of this end allows various unusual types of graphs to be created, such as Tornado Plots, Gantt Charts, etc.
Variable Origin graph setting
The Bar Origin role is activated when the line style is set to Bar, and the "Variable Origin" graph setup option is checked. When it is activated, a "Bar Origin" role pulldown appears in the graph result view, allowing the selection of a graph origin.
In Analytica 2.x and 3.x, a free-form field called "Bar Origin" appeared on the graph setup dialog. This field has been removed, and mechanism for controlling bar origin has been folded into the new Graphing Dimensions and Roles framework. However, Analytica 4.0 recognizes the legacy bar origin attribute and reflects it as if it has been defined as a graphing role. (defining a bar-origin in Analytica 4.0 will not, however, transfer back to 3.1).
When the Variable Origin graph setting is set, a couple other graph settings are automatically changed to the values that are common when creating a Tornado plot. Specifically, bar overlap is set to 100% and Swap-XY is checked. These can be subsequently unchecked if those settings are undesired.
Bar Origin Role Pulldown
When visible, the bar-origin role pulldown contains the following items:
- The constant "0"
- Each external value dimension
- Each coordinate column (if any)
- Each index dimension
- Each item from the Key index (if any)
Some items that appear in the bar-origin pulldown might not make sense as a bar origin. A dimension used as a bar origin should utilize the same units of measurement as the Y-axis dimension, for example. However, Analytica 4.0 does not enforce this. If a nonsensical dimension is used, the graph might not be sensible.
A bar-origin of 0 is the standard default, and essentially amounts to having no customized bar origin.
Selecting a value or index dimension (i.e., external value, coordinate column, or index dimension) causes the values from that dimension to control the position of "bottom end" of the bar (Note: this "bottom end" could be located on either side of the main value). When a bar-origin value contains indexes not in the main result, additional indexes appear in the plot.
The option to select a value from the current key index provides a convenient method for leaving one bar segment out. All bars are drawn from that key-item's value to each of the other values, and the selected key item is omitted from the key. For example, if a Key dimension contained the values ["Low", "Expected", "High"], each of these would appear as a choice in the bar-origin pulldown. Selecting "Expected" would create a Tornado-style bar chart, but would show only the ["Low", "High"] bar segments and key items -- with the bar segments starting at the "Expected" value.