Using apply functions

Question

I have a data frame having these columns

Qty  Sales Price  COGS  
  1          500   200  
  2          900   400   
  3         1000   300   
  1          300   150

I want to calculate the profit for every row. So for row 1 if Sales Price - COGS (500-200) profit is 300. one condition is that if qty is more than 1 then QtySales Prce- QtyCOGS= gross profit.

I used loop

for (i in 1:nrow(Data)) {
  if(Data[i,"Qty"]<=1) {Data[i,"Margin"]<-Data[i,"Sales.Price"]-Data[i,"COGS"]}    
  if(Data[i,"Qty"]>=1){Data[i,"Margin"]<-Data[i,"Qty" * "Sales.Price"]-Data[i,"Qty * "COGS"]}
}

But

I want to use apply function

and return my answer in data frame as Margin appended as an vector in my current data frame and not as list or matrix.

Qty    Sales Price    COGS    Margin  
  1            500     200       300  
  2            900     400      1000  
  3           1000     300      2100  
  1            300     150       150

Please read ?Arithmetic and then ?S4groupGeneric, many of the functions in R are vectorized (not only on vectors but on matrices and even data frames). Writing unnecessary loops in apply instead of a for won't get you far. — David Arenburg
– David Arenburg, Commented Jan 17, 2016 at 7:37

sgibb · Accepted Answer · 2016-01-17 07:34:43Z

2

There is no need for an apply function. You can just use a vectorized approach:

Data$Margin <- Data$Qty * (Data$Sales.Price - Data$COGS)

edited Jan 17, 2016 at 7:34

answered Jan 17, 2016 at 7:31

sgibb

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1 Comment

iamashish Over a year ago

Thanks for such a simple answer:)

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