CREATEEVENT

 

creates events along the routes in a route coverage.  Both LINEAR and POINT events can be created using this tool.  The events are created from points.  These points can either be digitized using the graphics cursor or supplied from an existing point coverage.  When CREATEEVENT is run without arguments a menu will be displayed (see createevent_main.hlp).  Otherwise, the following arguments are used for input.

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CREATEEVENT <event_source> <event_id_item> {1 | 2 | 2+} {DISSOLVE | NO} <point_cover> <point_item> {sort_item...sort_item}

 

ARGUMENTS

 

<event_source> - the existing event source which defines the event table to which events are to be added.

 

<event_id_item> - the item in the event table used to identify each event.  This item will be populated using the values from the <point_item>.  If the event table doesn't already exist, <event_id_item> will be created using the definition 34,34,C.

 

{1 | 2 | 2+} - defines how events are to be created:

 

1 (for LINEAR or POINT events) - create an event from each point.  In the case of linear events, each point is used to identify the upper limit of an event.  The events will be created from each point down to the beginning of the route system.

 

2 (for LINEAR events only) - create linear events using the points to define the upper and lower limits of each event.  The events will be created between the first and second points, the third and fourth points, etc.  The {sort_item...sort_item} are used to sequence the points prior to event creation.  The <point_item> value from the first point of each pair will be assigned to the <event_id_item>.

 

2+ (for LINEAR events only) - create linear events using the points to define a sequence of connected events.  The events will be created between the first and second points, the second and third points, etc.  The {sort_item...sort_item} are used to sequence the points prior to event creation.  The <point_item> value from the first point of each pair will be assigned to the <event_id_item>.

 

{DISSOLVE | NO} - whether or not to remove duplicate or overlapping events.  Only applicable for LINEAR events.

 

DISSOLVE - dissolve contiguous, duplicate or otherwise overlapping events which bear the same value in the <event_id_item>.  Overlapping events may get created by CREATEEVENT, especially using the {1} point option.  All events in the event table are processed, not just the new ones.

 

NO - events are not dissolved.

 

<point_cover> - the existing point coverage whose points are to be used to create events.

 

<point_item> - the item in the <point_cover> PAT which is used to identify each event.  The values from this item are written to the <event_id_item> in the event table.

 

{sort_item...sort_item} - the items in the <poin_cover> PAT which are used to sequence the points before they are used to create the events.

 

If no sort items are specified, then the points are processed in the order they appear in the coverage, i.e. by internal #.

 

If sort items are specified, then the points are sorted based on these items and processed in this order.

 

When creating events using the {1} point option, there may be no reason to sort the points.  However, when using the {2} point or {2+} point options, it may be necessary to sort the points first for the events to come out correctly.  For example, if your point coverage contains the upper and lower limits of several unconnected surveys, and each survey bears a unique ID, which has been assigned to each point, then use this survey ID item as the {sort_item}, and as the <event_id_item>.  Doing this will make sure that the points are sequenced by survey ID before they are used to create events via the {2} point option.

 

 

NOTES

 

CREATEEVENT runs from the ARCPLOT module of ARC/INFO.

 

MAPEXTENT must be set before running CREATEEVENT.

 

If any of the points fail to create events, flags are written to an item named CE_FLAG in the point coverage PAT, and a WARNING is displayed after all points are processed.  See the NOTES in createevent_main.hlp.

 

The points are processed in the order they appear in the coverage, i.e. by internal #, unless {sort_item...sort_item} are specified, in which case they are processed in sorted order.  Also, if a subset of the points have been RESELECTed, then only these points will be processed.