2014年4月9日 · Use subset.ffdf from package ffbase. Subset is a generic function in R, and ffbase implements it for ffdf objects. So you can just use subset as you would do with a regular data …

2012年9月18日 · Trying to learn about ffdf output, I entered command lines such as dim(B2010), str(B2010), ls(B2010), etc. dim(B2010) resulted in the appropriate number of rows but only …

2013年4月3日 · See ?as.ffdf or ?ffdf, part of the ff package. In real life, your data would be coming from other sources like csv or SQL sources instead of from a data.frame already in R. See …

I am trying to create an ffdf dataframe by merging and appending two existing ffdf dataframes. The ffdfs have different numbers of columns and different row numbers. I know that merge() …

2014年8月19日 · This is basically asking how to apply a previous question to a ffdf : R - applying ifelse to a whole data frame. I am basically trying to do the same thing. Given a ffdf dataframe, …

2015年7月23日 · I have a very large data set that I have to use as an ffdf, and am stuck trying to fill NA values using a last observation carried forward operation. Below is a sample of what the …

2014年3月3日 · The package ffbase provides many base functions for ff/ffdf objects, including subset.ff. With a bit of limited testing, it seems that subset.ff is relatively fast. Try loading …

2014年3月3日 · But I assume you have a ffdf with all columns of the same type, otherwise it does not make sense to convert it to an ff vector or ff matrix. If you want to convert to an ff matrix, …

2014年2月19日 · An ffdf is basically a list with elements "virtual", "physical", "row.names". If you do an lapply over the physical element, you have what you want.

2012年12月19日 · data <- read.csv.ffdf(file = fn, header = T, colClasses = classes) # file fn is a csv database with 5 columns and 2.6 million rows, # with some factor cols and some integer …