Hi all,
I would like to invoke a function that takes multiple arguments (some of
which are specified columns in the data frame, and others that are
independent of the data frame) on split parts of a data frame, how do I do
this?
For example, let's say I have a data frame
>fitness_data
name height weight country
rob 5.8 200 usa
nancy 5.5 140 germany
jen 5.6 150 usa
clark 5.10 210 germany
matt 5.9 280 canada
ralph 6 270 canada
...
...
Now let us say I have a function, my_func(h, w, noise, dir), which takes as
input:
(1) a vector of heights
(2) a vector of weights
(3) a user-input numeric "noise" value
(4) a user-input string "dir" for the directory to output the end result of
the function to
This function does some calculations on the input data and outputs a
dataframe that is then written to a file in the "dir" directory.
If I want to apply this function to data grouped by each country in the
"fitness_data" dataframe, how would I do this? I tried looking through the
mailing archives, but couldn't nail down the solution. I tried something
like
split(mapply( function(a,b,c,d) my_func(fitness_data$h, fitness_data$w, 2.5,
my_directory)), fitness_data$country)
but this considered fitness_data$h, and fitness_data$w in each single row
for a country, rather than a vector of heights or weights across all rows
corresponding to that country.
Thanks!
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