Hello,

I have the following dataset.  Please note that there are missing values on
records 4 and 5:

id,age,weight,height,gender
1,22,180,72,m
2,13,100,67,f
3,5,40,40,f
4,6,42,,f
5,12,98,66,
6,50,255,60,m

I'm using the "By" function like this:

list1 <- by(dataset[c("weight", "height")],
             dataset[c("age", "gender")],
             colMeans,
                          na.rm = TRUE)

I then convert the list above to a frame like this:

as.data.frame( do.call(rbind, list1) )

I get this output from the code above:

    weight height
1     40     40
2     42    NaN
3    100     67
4    180     72
5    255     60

I want to get the output above, but I also want two additional columns
named "age" and "gender" (with the age and gender values from the "By"
function output).

How would I do this?

Best Regards,

Ray DiGiacomo, Jr.
Healthcare Predictive Analytics Specialist
President, Lion Data Systems LLC
President, The Orange County R User Group
Board Member, TDWI
rayd@liondatasystems.com
(m) 408-425-7851
San Juan Capistrano, California USA
twitter.com/liondatasystems
linkedin.com/in/raydigiacomojr
youtube.com/user/liondatasystems/videos
liondatasystems.com/courses

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