Apr 9, 2014 · 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 frame.

Sep 18, 2012 · 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 one column (a string per record of the values separated by commas), and ls(B2010) outputted “[1] "physical" "row.names" "virtual" instead of the usual list of variables.

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() performs only inner and left outer joins while ffdfappend() will not allow appending if columns are not identical. I am wondering if anyone has a workaround for ...

Mar 3, 2014 · 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 ffbase and then using the simpler code you suggested from a …

Jul 23, 2015 · 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 data looks like I'm

Aug 13, 2012 · use ffdfappend from version 0.6 of the ffbase package. The ffdfappend of version 0.5 was designed to append a data.frame to an ffdf, while the one from version 0.6 also allows appending an ffdf to an ffdf.

Mar 3, 2014 · 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, you can use as.ff_matrix.ffdf which is unexported in ffbase, so access it with ffbase:::as.ff_matrix.ffdf as in the following example.

Feb 22, 2013 · If you pass a ffdf object instead of a data.frame, you run into one of the following two problems: ffdf is not a data.frame, so something undefined happens; the function to which you passed tries to convert ffdf to data.frame by e.g. as.data.frame(ffdf), which easily exhausts your RAM, this likely is what happend to you

Aug 19, 2014 · 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, I am basically asking how to apply an ifelse to the entire dataframe. See the two examples that work on test (a data frame). I'm trying to do the same to test.ffdf.

Dec 19, 2012 · 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 cols. data.1 <- data save.ffdf(data.1 , dir = my.dir) # my.dir is a string pointing to the file.