this might be a trivial question (eventually sorry for that!) but I definitely can not catch the problem here...
please consider the following reproducible example: why of different results through 'split-lapply' vs. 'aggregate'?
I've been also through a check against different methods (e.g. data.table, dplyr) and the results were always consistent with 'split-lapply' but apparently not with 'aggregate'
I must be certainly wrong!
could someone point me in the right direction?
thanks
##
s <- split(airquality, airquality$Month)
ls <- lapply(s, function(x) {colMeans(x[c("Ozone", "Solar.R", "Wind")], na.rm = TRUE)})
do.call(rbind, ls)
# slightly different results with
aggregate(.~ Month, airquality[-c(4,6)], mean, na.rm=TRUE)
##
'split-lapply' vs. 'aggregate'
2 messages · Massimo Bressan, John Fox
Dear Massimo, The difference is in the handling of NAs. Try, e.g., airquality <- na.omit(airquality) and compare again. Best, John ----------------------------- John Fox, Professor McMaster University Hamilton, Ontario Canada L8S 4M4 web: socserv.mcmaster.ca/jfox
From: R-help [r-help-bounces at r-project.org] on behalf of Massimo Bressan [massimo.bressan at arpa.veneto.it]
Sent: March 27, 2016 5:45 PM
To: r-help at r-project.org
Subject: [R] 'split-lapply' vs. 'aggregate'
Sent: March 27, 2016 5:45 PM
To: r-help at r-project.org
Subject: [R] 'split-lapply' vs. 'aggregate'
this might be a trivial question (eventually sorry for that!) but I definitely can not catch the problem here...
please consider the following reproducible example: why of different results through 'split-lapply' vs. 'aggregate'?
I've been also through a check against different methods (e.g. data.table, dplyr) and the results were always consistent with 'split-lapply' but apparently not with 'aggregate'
I must be certainly wrong!
could someone point me in the right direction?
thanks
##
s <- split(airquality, airquality$Month)
ls <- lapply(s, function(x) {colMeans(x[c("Ozone", "Solar.R", "Wind")], na.rm = TRUE)})
do.call(rbind, ls)
# slightly different results with
aggregate(.~ Month, airquality[-c(4,6)], mean, na.rm=TRUE)
##
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