apply

I'm working through an R tutorial and suspect that I have to use one of these functions but I'm not sure which (Yes I researched them but until I become more fluent in R terminology they are quite confusing). In my working directory there is a folder "specdata". Specdata contains hundreds of CSV files named 001.csv - 300.csv. The function I am working on must count the total number of rows for an inputed number of csv files. So if the argument in the function is 1:10 and each of those files has ten rows, return 100. Here's what I have so far: complete <- function(directory,id = 1:332) {

I don't understand why apply and transform return different dtypes when called on the same data frame. The way I explained the two functions to myself before went something along the lines of " apply collapses the data, and transform does exactly the same thing as apply but preserves the original index and doesn't collapse." Consider the following. df = pd.DataFrame({'id': [1,1,1,2,2,2,2,3,3,4], 'cat': [1,1,0,0,1,0,0,0,0,1]}) Let's identify those id s which have a nonzero entry in the cat column. >>> df.groupby('id')['cat'].apply(lambda x: (x == 1).any()) id 1 True 2 True 3 False 4 True Name:

I am getting strange results when using inline function. Here is the code: IF EXISTS ( SELECT * FROM sys.objects AS o WHERE name = 'vendor_relation_users' ) DROP FUNCTION dbo.vendor_relation_users; GO CREATE FUNCTION [dbo].[vendor_relation_users] ( @user_name CHAR(12) ) RETURNS TABLE AS RETURN (SELECT @user_name AS user_name WHERE @user_name NOT LIKE '06%'); GO DECLARE @u CHAR(12) = '066BDLER' SELECT a.user_name, is_v.user_name FROM (SELECT @u AS user_name) a OUTER APPLY [dbo].[vendor_relation_users](@u) AS is_v SELECT a.user_name, is_v.user_name FROM (SELECT @u AS user_name) a OUTER APPLY

In R, how do you replace the following code using functions like apply , lapply , rapply , do.call , etc.? u <- 10:12 slist <- list() for (i in 1:length(u)) { p <- combn(u, i) for (j in 1:ncol(p)) { s <- paste(p[,j], collapse=",") slist[[s]] <- 0 } } For this part: for (j in 1:ncol(p)) { s <- paste(p[,j], collapse=",") I tried something like: s <- apply(p, 2, function(x) paste(x, collapse=",")) Which works. But then for that slist[[s]] <- 0 part inside that same for-loop, I don't know what to do. Edit: This is what I'm trying to do. For the vector u , I'm producing a list of all the subsets in