R help - Jan 2014 - R 3.0.2 How to Split-Apply-Combine using various Columns

Hello everyone,
I have a large vehicle trajectory data of which following is a small part:
 
	
	
		
			vehicle
			frame
			globalx
			class
			velocity
			lane
		
		
			1
			221
			6451260
			2
			23.37
			5
		
		
			1
			222
			6451261
			2
			23.16
			5
		
		
			1
			223
			6451263
			2
			22.94
			5
		
		
			1
			224
			6451264
			2
			22.85
			5
		
		
			2
			115
			6451181
			3
			35
			4
		
		
			2
			116
			6451184
			3
			35.01
			4
		
		
			2
			117
			6451186
			3
			35.03
			4
		
		
			2
			118
			6451188
			334.92
			4
		
		
			2
			119
			6451191
			334.49
			4
		
		
			2
			120
			6451193
			333.66
			4
		
		
			2
			121
			6451195
			332.5
			4
		
	

vehicle = unique ID of vehicle. It is repeated (in column) for every frame in
which it was observedframe= ID of the frame in which the vehicle was observed.
One frame is 0.1 seconds long.class = class of vehicle i.e. 1=motorcycle, 2=car,
3=truckvelocity= velocity of vehicle in feet per secondlane= lane number in
which vehicle is present in a particular frame
'frame' number can also repeat e.g. in frame 120 the example data shows
vehicle 2 was observed but in the original data many more vehicle might have
been observed in this frame. Similarly, 'class' is defined above and all
three classes are present in the original data (here example data only shows
classes 2 and 3 i.e. cars and trucks).
I need to determine two things:1) Number of vehicles observed in every 30
seconds i.e. 300 frames2) Average velocity of each vehicle class in every 30
seconds
This means that the first step might be to determine the minimum and maximum
frame numbers and then divide them in slots so that every slot has 300 frames.
In my original data I found 22 as min and 9233 as max frame number. This makes
30 time slots as 22-322, 322-622, ..., 9022-9233. I need following output:

	
	
		
			Timeslot
			lane
			Totalcars
			Totaltrucks
			Totalmotorcycles
			AverageVelocity-cars
			AverageVelocity-trucks
			AverageVelocity-motorcycles
		
		
			22-322
			

			

			

			

			

			

			

		
		
			322-622
			

			

			

			

			

			

			

		
		
			622-922
			

			

			

			

			

			

			

		
		
			.
			

			

			

			

			

			

			

		
		
			.
			

			

			

			

			

			

			

		
		
			.
			

			

			

			

			

			

			

		
		
			9022-9233
			

			

			

			

			

			

			

		
	


I have tried many things and also used some suggestions from stackoverflow but
still am unable to get output like this with input data. Please help.



Umair Durrani

email: umairdurrani@outlook.com
 		 	   		  
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