updated: 21-Sep-2010

 Copan for Windows

Point Filters

At times you may wish to view or work with a specific subset of points from an open coordfile, rather than the whole file. You can establish such a subset by specifying a filter (or query). Typically, to specify a filter, you just identify sequences or ranges of point numbers. You can, however, also identify ranges of coordinate values, as well as conditions for the three alphanumeric fields.

1. To Filter Points

1. Click the Filter... button from whichever module is processing a group of points
   or choose Viewing & Printing | Filter Points... to restrict the viewing of points.
2. Optionally, select an existing filter from the Filter list box.
3. Enter or edit the details of the filter (see Filter Criteria below).
4. Optionally, enter a new name for the filter in the Filter list box.
5. Click OK.

2. Filter Criteria

• A Point # expression lists individual and ranges of point numbers. The syntax is just like the way page ranges in many print dialogs are specified:

  point-expression

  point-range

  point-range   ,   point-expression

  point-range

  point-number

  point-number   -   point-number

  For example, a Point # expression of  1-99, 110, 250-349, 900  means Points 1 to 99, 110, 250 to 349, and 900.
• The Min and Max Northing and Easting values are inclusive extremes. For example,
  • A Min and Max Northing of  290  and  380  means 290 <= northing <=380.
  • A Min Easting of  150.2  means easting >= 150.2.
• Because points can have null or missing elevations, there are three mutually exclusive Elevation options:
  • If you only want 2D points, choose 2D only.
  • If you only want 3D points, choose 3D only.
  • If you want 2D and 3D points, choose Irrelevant.
• To enter Elevation extremes, you must choose the 3D only option.
  • A Min and Max Elevation of  10  and  30  means 10 <= elevation <=30.
• Criteria based on Name, Code, or Note fields require text expressions.

3. Text Expressions

Syntax

In these quasi-formal syntax definitions, a defined term (outdented) is followed by its definition (indented), with alternative definitions separated by vertical lines or on separate lines. Puzzled? See the Examples.

text-expression

predicate

text-expression   logical-operator   text-expression

( text-expression )

predicate

relational-operator   value

relational-operator

= | ? | != | <> | < | > | <= | >=

value

any text | " any text containing a special character "

logical-operator

& | ,

Relational and Logical Operators

Examples

4. Notes

• If criteria are entered for more than one attribute, the conjunction between them is assumed to be logical and. Thus, for example, if both Point # and Code expressions are entered, the filter will allow only points simultaneously meeting both sets of criteria.
• There is currently no way of specifying a logical or between different field criteria.
• There is currently no way of saying not containing.
• There is currently no way of specifying criteria for other attributes (e.g., Locked, Modified, etc).
• The full syntax for the criteria expressions may evolve. Give us your suggestions.
• By default, after you filter some points for whatever reason, only those points passing the filter are immediately viewable. To make all points viewable, regardless of the current filter, do one of two things:
  • either select Viewing & Printing | Ufilter Points, each time you need to,
  • or, for a lasting choice, select Program | Settings... | General... and check Ignore filter when viewing points under Logistics.

  updated: 21-Sep-2010

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