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?
filter -format filtername format
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. | Format | A format for the output filter file. |
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. |
| format | A string that selects a filter output format. SpecTcl has the xdr filter output format built in. SpecTcl plugins can provide other filter types. The usage string for the filter command (e.g. just type filter) provides a list of known format strings and their meanings. |
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 *
To set the format of the output filter file (only legal when the filter is disabled), use the -format switch:
filter -format filtername formatwhere filtername is the name of a filter and format is a string identifying the format.
If you never specify a format, the default is
xdr
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. , and the format is the
xdrformat.
The example below modifies the filenames for the two filters:
% filter -filename george.flt george
george Band1 /user/fox/filter.flt {Distribution1
Distribution2} disabled xdr
% filter -filename harry.flt harry
harry Band1 harry.flt {Distribution3} disabled xdr
%
Both filters are still disabled. The following enables the two filters:
% filter -enable george
george Slice george.flt {Distribution1 Distribution2}
enabled xdr
% filter -enable harry
harry Band1 harry.flt {Distribution3} enabled xdr
%
Suppose a plugin add the filter type
rootthat writes root output trees we can set the filter output format for george as follows:
Last Modified: October 28, 2003
by: fox@nscl.msu.edu
© Copyright NSCL 1999, All rights reserved