Hello , I'm new to R and don't really understand how to use the function "apply" instead of a "for loop", particularly for a function with multiple entries. I have a big data file and would like to apply a function in multi thread to accelerate the processus.
I have a data frame containing values of* CO2 in ppm (resp[i,6])* that I want to convert in umol of CO2 emitted by stem volume biomass (CO2v) and stem area (CO2s). (tree respiration) The loop that I have is calculating the CO2 fluxes for each row. *Script :* for (i in 1:nrow(resp)) { k=resp[i,5] CO2umol[i]<-resp[i,6]*((Press*infoch[k,11]*1e-6)/(R*(resp[i,7]+273.15))) CO2v[i]<-CO2umol[i]/(infoch[k,10]) CO2s[i]<-CO2umol[i]/(infoch[k,9]) } For that, I have two data frames : - *infoch :* variables used to calculate CO2 fluxes (16 rows with the characteristics of 16 analysis chambers) <http://r.789695.n4.nabble.com/file/n4649326/infoch.jpg> - *resp: *time series containing CO2 values and temperatures by chamber analysed (more than 500.000 rows) <http://r.789695.n4.nabble.com/file/n4649326/resp.jpg> other variables : Press=93000 R=8.31 The loop is working good, but taking quite a long time to process, if someone could explain me how to use the apply function in this case, it would be really helpful. Thanks Charles -- View this message in context: http://r.789695.n4.nabble.com/Using-apply-instead-of-for-loop-multithreading-tp4649326.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.