how to prevent dataframe columns being classed as character instead of numeric
dataframe, r
Solution
`cbind("A",5,360)` is a matrix, which can hold only one type, i.e. character in your case.
Use the data.frame method:
cbind.data.frame("A",5,360)
However, "cycling through some data" is probably the least efficient way to do this in R.
Problem
Good morning. I am cycling through some data, building a dataframe as I go. Every time I add or replace a row in the dataframe, numeric values get classed as character, and I have to re-class them. I assume I am doing something wrong when adding the data to the dataframe ? ``` test.df<-data.frame(SIDE=rep("",5),n=rep(NA, 5),c1=rep(NA,5),stringsAsFactors=FALSE) test.df[1,]<-cbind("A",1,256) test.df[2,]<-cbind("A",2,258) test.df[3,]<-cbind("A",3,350) test.df[4,]<-cbind("A",4,400) test.df[5,]<-cbind("A",5,360) summary(test.df) SIDE n c1 Length:5 Length:5 Length:5 Class :character Class :character Class :character Mode :character Mode :character Mode :character ``` Convert the numeric columns to numeric: ``` test.df[, c(2:3)] <- sapply(test.df[, c(2:3)], as.numeric) summary(test.df) SIDE n c1 Length:5 Min. :1 Min. :256.0 Class :character 1st Qu.:2 1st Qu.:258.0 Mode :character Median :3 Median :350.0 Mean :3 Mean :324.8 3rd Qu.:4 3rd Qu.:360.0 Max. :5 Max. :400.0 ``` So the dataframe is now as I expect it - 1 column of character data and 2 of numeric. However if I change one of the rows again: ``` test.df[5,]<-cbind("A",5,360) summary(test.df) SIDE n c1 Length:5 Length:5 Length:5 Class :character Class :character Class :character Mode :character Mode :character Mode :character ``` it has gone back to all character! Is there any way to ensure that when I append/change data in the dataframe that it keeps the appropriate classes ? Thanks, Pete