Jonas Lindeløv - 7 months ago 38

R Question

I have a relatively large dataset, and I want to print a table of means and standard deviations for combinations of factors. I would like to have them in a format like this:

`A B`

test1 2.0 (1.0) 5.0 (2.0)

test2 6.3 (3.1) 2.1 (0.7)

Is there an easy way to do this?

The closest I get is using the

`tables::tabular`

`# Example data`

df = data.frame(

group=c('A', 'A', 'A', 'B', 'B', 'B'),

value=c(1,2,3,6,8,9))

# Print table

library(tables)

tabular(value ~ group * (mean + sd), df)

... which outputs this:

`group`

A B

mean sd mean sd

value 2 1 7.667 1.52

But I haven't figured out a neat way to transform this format to the

`mean (SD)`

Answer

```
library(reshape2)
formatted.table <- dcast(df, 'value' ~ group, fun.aggregate = function(x) {
return(sprintf('%0.1f (%0.1f)', mean(x), sd(x)))
})
# "value" A B
# value 2.0 (1.0) 7.7 (1.5)
```

Similar to Chris's answer, but a little bit cleaner (and no "test" variable needed).

You can also do this type of aggregation with the `dplyr`

package.