Unit conversions

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Question

How to convert data from one unit to another in R?

Answer

We need conversion factors, which are listed below, and a code that does the actual conversion.

Unit conversions(-)

Obs	From	To	Factor	Description
1	MWh	MJ	3600	1 MWh = 1 MWh * 3600 s/h = 3600 MWs = 3600 MJ
2	toe	MJ	35000	1 toe = 1000 kgoe = 1000 kg * 35 MJ/kg = 35000 MJ

+ Show code- Hide code ############# Unit.convert: a function that converts units from one to another, if possible. # value = a numeric vector with values to be converted # fromunit = a numeric vector with the current units # tounit = a string for the new units to be used. Must be found from the To column from the table in [[Unit conversions]]. # expo = exponent for the conversion. If -1 converts the inverse, i.e. backward, or a unit that is in the denominator of a compiled unit. unit.convert <- function(value, fromunit, tounit, expo = 1) { data <- tidy(op_baseGetData("opasnet_base", "Op_enXXXX")) out <- merge(fromunit, data, by.y = data$From) out <- out[out$To == tounit, ] out <- merge(value, out, all.x = TRUE) out <- out$value * out$Factor^expo return(out) }

⇤--#: . The code does not work because the merges and combinations do not match. Values should have some row identifier that makes it possible to link a row in value to the right row in out. Should value and fromunit be two columns in a data.frame? --Jouni 11:29, 25 January 2012 (EET) (type: truth; paradigms: science: attack)