FAQ Database Discussion Community


How to DROP columns from ffdf object ? (R)

r,ff,ffbase
Could I easily drop column of ffdf object ? library(ff);library(ffbase) irisdf=as.ffdf(iris) How to contain only Sepal.length and Species columns ?...

Current status of colClasses argument in function ff:read.csv.ffdf (ff - R package)

r,ff,read.csv
Error vmode 'character' not implemented occours due to argument colClasses=c("id"="character") in below code : df <- read.csv.ffdf('TenGBsample.csv', colClasses=c("id"="character"), VERBOSE=TRUE) read.table.ffdf 1..1000 (1000) csv-read=0.02secError in ff(initdata = initdata, length = length, levels = levels, ordered = ordered, : vmode 'character' not implemented where first column in TenGBsample.csv is 'id' and consist...

R - ff package : find the most frequent element in ffdf and delete the rows where is located

r,data.frame,ff,ffbase
I need a suggestion to find the most frequent element in ffdf and after that to delete the rows where is located. I decided to try the ff package as I'm working with very big data and with base R I am running out of memory. Here is a little...

Grow a ffdf data frame on disk gradually

r,ff,ffbase
From documentation of save.ffdf: Using ‘save.ffdf’ automagically sets the ‘finalizer’s of the ‘ff’ vectors to ‘"close"’. This means that the data will be preserved on disk when the object is removed or the R sessions is closed. Data can be deleted either using ‘delete’ or by removing the directory where...

Converting “individual clock in/out time logs” to “total occupancy of building over time” efficiently

r,bigdata,ff
So I have data in .csv form showing the time which specific users walks into and out of a building over a few months. I am trying to use R to tabulate the building occupancy every 15/30 minutes for analysis. The data has been cleaned and is in the form...