filter - SpecTcl Command
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filter - SpecTcl Command |
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SpecTcl Home General Information User Guide Programmer's Guide Obtaining and Installing
filter [-new] filtername gatename {par1 par2 ...}
filter -delete filtername
filter -enable filtername
filter -disable filtername
filter -regate filtername gatename
filter -file filename filtername
filter -list ?glob-pattern?
Creates, modifies, enables, lists and deletes filters:
SpecTcl maintains a dictionary of Filters. A filter consists of:
| Item | Description |
| Name | A name that is used to refer to the filter in future operations. |
| Gate | A gate that determines which events pass the filter. |
| Filename | The name of a file to which the passed events are written |
| Parameter List | The set of parameters that are written for passed events |
| State | A flag that indicates if the filter is active (enabled) or inactive (disabled). Note: Filters are created in the disabled state. |
The filter command allows you to define and manipulate these parameters.
A filter does nothing until it is enabled. Once enabled, it opens its output file and begins to produce filtered event streams on its output file. See the filter section of the programming guide for a description of how to read back filtered files.
The following syntax creates a filter:
filter [-new] filtername gatename {par1 par2 ...}
Note that the -new switch is optional. If the filter command does not have a command switch, the default action is to create a new filter.
| Parameter | Meaning |
| filtername | The name of the filter. This name will be used to refer to the filter in future filter commands. |
| gatename | This is the name of a previously existing gate. When the filter is enabled, this gate is checked against each event. For each event that makes the gate true, an output event is written in the event file. |
| {par1 par2...} | A TCL list of the names of defined parameters. Each event that is written to the output stream contains those and only those parameters. Note that parameters that have not been assigned to in the event processors are never passed to the output file. |
To delete a filter:
filter -delete filtername
Where filtername is the name you assigned to a filter when you created it.
To enable an existing filter:
filter -enable filtername
Where filtername is the name you assigned to the filter when you created it.
Filters are created in the disabled state. Once enabled, filters open their output files and start writing filtered event data to them. When this command is successful it will return a description of the filter that was enabled.
To disable an existing filter:
filter -disable filtername
Where filtername is the name you assigned to the filter when you created it.
Filters are created in the disabled state. once enabled, filters open their output files and start writing filtered event data to them. To close the filter's output file and stop filtering the incoming event stream, disable the filter.
To change the gate on a filter, use the command:
filter -regate filtername gatename
filtername is the name of the filter you created. gatename is the name of an existing gate that will be applied to the filter. When enabled, this gate will be used to select events that are written to the output file.
The output of a successfull filter -regate command is a description of the gate.
To set the filename of the filter:
filter -file filename filtername
The filename defaults to ~/filter.flt so if you have more than one filter, it is a good idea to set a new filename for each filter.
To list the set of filters that are known to SpecTcl:
filter -list
or alternatively
filter -list pattern
The first form lists all filters known to SpecTcl, The second form lists the filters whose names match pattern. pattern may contain "glob" wildcard characters. For example, the first command is equivalent to :
filter -list *
In the examples below, SpecTcl's output is given in red.
The example below creates two filters named george and harry:
% filter george Slice {Distribution1 Distribution2}
george Slice /user/fox/filter.flt {Distribution1 Distribution2} disabled
% filter harry Band1 Distribution3
harry Band1 /user/fox/filter.flt {Distribution3} disabled
For george, only the parameters Distribution1 and Distribution2 are written to the output filter file. For Harry, only Distribution3 is written. Note that both filters are disabled, and the filenames for both filters are the same.
The example below modifies the filenames for the two filters:
% filter -filename george.flt george
harry Band1 /user/fox/filter.flt {Distribution3} disabled
% filter -filename harry.flt harry
harry Band1 harry.flt {Distribution3} disabled
%
Both filters are still disabled. The following enables the two filters:
% filter -enable george
george Slice george.flt {Distribution1 Distribution2} enabled
% filter -enable harry
harry Band1 harry.flt {Distribution3} enabled
%
Last Modified: October 28, 2003
by: fox@nscl.msu.edu
© Copyright NSCL 1999, All rights reserved