How to access single elements in a table in R - Stack Overflow
Feb 1, 2012 · Using the term "table" to refer to that structure leaves open the possibility that it was either a 'table'-classed, or a 'matrix'-classed, or a 'data.frame'-classed object. The answer above would succeed with any of them, while @BenBolker's suggestion below would only succeed with a 'data.frame'-classed object.
How to join (merge) data frames (inner, outer, left, right)
Below benchmark tests base R, sqldf, dplyr and data.table. Benchmark tests unkeyed/unindexed datasets. Benchmark is performed on 50M-1 rows datasets, there are 50M-2 common values on join column so each scenario (inner, left, right, full) can be tested and join is still not trivial to perform. It is type of join which well stress join algorithms.
r - best way to transpose data.table - Stack Overflow
Feb 22, 2015 · Here's a solution that uses a wrapper to tidy up the output of the data.table transpose function.. With really large data sets this seems to be more efficient than the dcast/melt approach (I tested it on a 8000 row x 29000 column data set, the below function works in about 3 minutes but dcast/melt crashed R):
R table with where condition - Stack Overflow
Sep 3, 2013 · I have a simple table (age by marital status) for individuals in a range of geographical zones. I'd like to produce a table for each of these, would this be possible to do using a where statement, something along the lines of : …
How do you delete a column by name in data.table? - r
Feb 9, 2012 · data.table also supports the following syntax: ## Method 3 (could then assign to df3, df3[, !"foo"] though if you were actually wanting to remove column "foo" from df3 (as opposed to just printing a view of df3 minus column "foo" ) you'd really want to use Method 1 instead.
r - Sort a data.table fast by Ascending/Descending order - Stack …
Dec 3, 2012 · sort by ascending Year, ascending MemberID, descending Month. Is there an equivalent way in data.table to do this? So far I have to break it down into 2 steps: setkey(X, Year, MemberID) This is very fast and takes only a few second. X <- X[,.SD[order(-Month)],by=list(Year, MemberID)] This step takes so much longer (5 minutes). Update: Someone ...
r - How to convert a table to a data frame - Stack Overflow
Short answer: using as.data.frame.matrix(mytable), as @Victor Van Hee suggested. Long answer: as.data.frame(mytable) may not work on contingency tables generated by table() function, even if is.matrix(your_table) returns TRUE. It will still melt you table into the factor1 factor2 factori counts format.
How to get proportions and counts of a data frame in r
Jul 7, 2013 · Getting both column counts and proportions in the same table in R. 5.
Remove a row from a data table in R - Stack Overflow
May 19, 2016 · I want to create a data table that looks like this: Row number tracking_id 3D71 3D72 3D73 1 yyy 2 2 2 2 zzz 3 3 3. i.e. I want to delete all of row number 1 and then shift the other rows up. I have tried datatablename [-c (1)] but this deletes the first column not the first row! Many thanks for any help! r. edited May 18, 2016 at 18:30.
dataframe - Aggregating table() over multiple columns in R …
Jun 8, 2015 · I have a 2-column data frame of x- and y-coordinates of points. I want to generate a table of the number of occurrences of each point. Using the table() command produces a table for all possible x-y