I have the following data frames, avGain and retGain.  They have the same
dimensions.

 

The following line of code replaces row j of avGain as desired:

 

avGain[j, ] <- mean( retGain[jStart:j, ] )

 

However, the following line does not work:

 

avGain[j, ] <- ( avGain[j-1, ] * ( DAYS - 1 ) + retGain[j, ] ) / DAYS

 

If I do the following, and test to see if a or b are data frames.

 

a <- mean( retGain[jStart:j, ] )

b <- ( avGain[j-1, ] * ( DAYS - 1 ) + retGain[j, ] ) / DAYS

 

I find that a is not, but b is indeed a data frame.  I guess this is part of
my problem.

 

Does anyone know why one works and the other doesn't, and how I can replace
a row of a data frame with another data frame?


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