Summary: tapply()

[Winnie Lambert <lambert.winifred@ensco.com>]

All,

 

Sincere thanks to all who suggested to make $Hour a factor:

 

Russel Zaretzki

Samuel Buttrey

Vadim Kutsyy

Nick Ellis

Bill Dunlap

Glenn Treacy

Bob Byers

Terry Therneau

 

The actual command that worked was

 

> tapply ( get(infile)$Spd[good.s], as.factor( get(infile)$Hour )[good.s], mean )

 

If you use this, make sure that the [good.s] is outside the function call to as.factor()

The same worked for the length with an extra command to change the NA to 0

 

> x <-  tapply( get(infile)$Spd[good.s], as.factor( get(infile)$Hour )[good.s], length )

> x[is.na(x)] <- 0

 

Thanks again.  The responses were really fast and useful.

 

Win Lambert