R-create a data frame inside this loop

Question

How can I create a data frame inside this loop based on the calculated variables?

Script:

for (i in  1:nrow(newData)){
  X<-newData[i,1]
  Y<-newData[i,2]
  dRatio <- ((X-Xmean)/(Y-Ymean)) 
  dataList <- data.frame(X,Y,dRatio)
}

dataList = cbind(newData[,1], newData[,2], (newData[,1]-Xmean)/(newData[,2]-Xmean)) — Vlo
– Vlo, Commented Oct 21, 2016 at 14:48

989 · Accepted Answer · 2016-10-21 15:00:51Z

1

Try this vectorized:

dataList <- newData[,1:2]
dataList$dRatio <- ((newData[,1]-Xmean)/(newData[,2]-Ymean))

Or if you persist to use your own code:

m <- matrix(0, nrow(newData), 3)
for (i in  1:nrow(newData)){
  X<-newData[i,1]
  Y<-newData[i,2]
  dRatio <- ((X-Xmean)/(Y-Ymean)) 
  m[i,] <- c(X,Y,dRatio)
}
dataList <- as.data.frame(m)

edited Oct 21, 2016 at 15:00

answered Oct 21, 2016 at 14:52

989

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Comments

user124123 · Accepted Answer · 2016-10-21 14:48:54Z

1

You could create a list to hold dataframes outside of your loop

dataList<-list()
for (i in  1:nrow(newData)){
  X<-newData[i,1]
  Y<-newData[i,2]
  dRatio <- ((X-Xmean)/(Y-Ymean)) 
  dataList[[i]] <- data.frame(X,Y,dRatio)
}

answered Oct 21, 2016 at 14:48

user124123

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2 Comments

elyraz Over a year ago

this create a list, any way to create a data frame?

user124123 Over a year ago

This will create a list of dataframes.

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