Using Object Selection Filters
Object filtering enables you to search for objects based on certain attributes. For example, you could use object filtering to select all circles in a drawing with a specific radius. To invoke object filtering, type the command FILTER at the SelectObjects: p rompt. This displays the Object Selection Filters dialog box (see Figure 11.20).
Figure 11.20. The Object Selection Filters dialog box is a robust filtering system with the added capability to save filter lists for later use.
You can assemble a list of the properties, also known as filter criteria, with which you want to conduct the search. Then, by clicking the Apply button, you can select a group of objects within which you want to find those objects that meet your list of characteristics. The following sections discuss how to define your list of filters.
Defining Simple Selection Criteria for Filters
A filter can be a type of object, a characteristic of that type of object, or defined from an object property. For example, you can search for arcs in general or arcs that have a specific radius. The list of available filters is extensive and is displayed in the Filters drop-down list. If you choose a characteristic of an object, you also must supply the specific value of that characteristic that you seek within the X edit box, located below the filter list. For some filter selections, you can click the Select button to choose the specific value from a list of existing or valid values. For other properties, you must type that value in the edit box.
After you select the filter and its associated value (if any), click the Add to List button to add the selected filter to the list at the top of the dialog box. To select the objects to which your filter criteria will be applied, click the Apply button.
To remove a filter from the list, choose the filter and click Delete. To edit the specific value of a filter in the list, select the filter and click Edit Item. After changing the value of the property, click Substitute to replace the old property with the revised property.
Defining a Complex Selection Criteria for Filters
The search criteria employed can be a complex set consisting of multiple filters. By default, when you assemble a list of filters, only objects that meet all the individual filters in the list are selected. For example, you could choose to select only arcs that reside on the layer CURVES by choosing the Arc and Layer filters. In doing so, you assemble a list of properties that must be met; this is referred to as an AND conditional. When you assemble a list of properties, the system assumes that you are assembling an AND conditional filter list. Other options do exist, however.
The most common option is to create an OR conditional filter list. In an OR conditional, the objects must meet only one of the conditions, not all of them. For example, you could assemble a list of properties such that any object that is an arc or that resides on the CURVES layer is selected. You begin an OR conditional by choosing the **Begin OR filter. Then you assemble the various properties in which you are interested. You end the list of properties with the **End OR filter.
The list of filters can consist of AND and OR conditionals nested within each other, but for most users a simple search criteria consisting of a single conditional filter is enough.
Tip
To gain an idea of the properties that are available for a particular object, click the Add Selected Object button and select an object in your drawing. All the relevant filters and their specific values for the selected object automatically are assembled into a list. You then can delete the filters you do not need, leaving only the properties for which you want to search.
Saving and Restoring the Criteria for Filters
To save a list of filters you have assembled so the list can be reused at a later date or in another drawing, type a name in the Save As edit box and click Save As. The next time you want to use that filter, simply select its name from the Current drop-down list. To delete a named filter, select the name from the Current drop-down list and click Delete Current Filter List. Named filter lists are saved in the file FILTER.NFL, which is created in the current working directory when you initially click the Save As button.
Exercise 11.4 Using the Filters to Assemble Selection Sets
1. |
Open the CHAP11-1.dwg from the CD that accompanies this book. This office plan includes many object types for using filters. |
2. |
From the Tools pull-down menu, choose the Quick Select menu option. The QSELECT dialog box will appear. |
3. |
From the Object type list box, choose Line. Then click OK to close the command. The system then highlights 336 line objects in the drawing. Now you need to refine this selection to fewer objects. |
4. |
Press Enter to restart the QSELECT command. From the Properties list box, choose Layer, and then in the Value list box choose 1FL_WALL. Click OK to close the dialog box. |
5. |
AutoCAD then replaces the 336-object selection set with a 274-object selection set and highlights it for you. You’re not done, so press Enter to restart the QSELECT command. |
6. |
Be sure that the object type list box is still set to Line. Then from the Properties list box, choose Start Y. Change the Operand to > Greater Than. In the Value edit box, type 77'3"
. Then click OK to close the dialog box. |
7. |
AutoCAD then selects and highlights all the line objects on layer 1FL-WALL with a Y start point greater than 77'-3". These objects are now available for general editing such as a COPY or MOVE command. If you need to save and restore a selection set, you must use the FILTER command. The rest of the exercise demonstrates this method. |
8. |
Type Filter
at the command line and press Enter. |
9. |
In the Select Filter area, choose Line from the list box and click the Add to List button. This adds a filter for line objects only. |
10. |
From the Select Filter area, choose Line Start. Change the X and Z operands to * from their list box and type 0
in each of the edit boxes. Change the Y operand to > and in its edit box type 77'3"
. Then click the Add to List button. This adds a filter for coordinates in any X and Z location but only points greater than 77'-3" in the Y direction. |
11. |
From the Select Filter area, choose Layer. Click the Select button and choose 1FL_WALL from the listing; then click OK. Click Add to List to add this required layer name to match against. In the Named Filters area, locate the edit box to the right of the Save As button. Type North Walls
and click the Save As button. The current filter name then changes from *unnamed to North Walls. |
12. |
Click the Apply button at the bottom of the Objects Selection Filters dialog box. This closes the dialog box and prompts you to select objects. Type ALL
and press Enter. Then press Enter again to end the Select Objects request. This then applies the filters to all the objects in the drawing and prepares a specific selection set matching your North Walls filter criteria. |
13. |
Press Enter to restart the FILTER command. You will notice that your filter parameters are still available and the name set. Click the Clear List button. The filter parameters will disappear. |
14. |
Now choose North Walls from the Current name list. Notice that the filters criteria reappears in the list area. Click the Delete Current Filter List button to remove the saved list and clear the filter area. Then click Cancel to exit the dialog box. Now you may exit this drawing; there is no need to save it. |
In addition to searching for objects that share certain properties, you can also gather up objects and place them in named groups for later retrieval. The next section explains this process in detail.