Hi,
I have data stored in a list that I would like to aggregate and perform some
basic stats. However, I would like to apply conditional statements so that not
all the data are used. Basically, I want to get a specific variable, do some
basic functions (such as a mean), but only get the data in each element's data
that match the condition. The code I used is below:
> result<-sapply(res, function(.df) { #res is the list containing file data
+ if(.df$Volume>0)mean(.df$Volume) #only have the mean function calculate on
values great than 0
+ })
I did get a numeric output; however, when I checked the output value the
conditional was ignored (i.e. it did not do anything to the calculation)
I also obtained these warning statements:
Warning messages:
1: In if (.df$Volume > 0) mean(.df$Volume) :
the condition has length > 1 and only the first element will be used
2: In if (.df$Volume > 0) mean(.df$Volume) :
the condition has length > 1 and only the first element will be used
Please let me know what am I doing wrong and how can I apply a conditional
statement to the sapply function.
Thanks
Mark
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