subset

I'm working on a puzzle that involves analyzing all size k subsets and figuring out which one is optimal. I wrote a solution that works when the number of subsets is small, but it runs out of memory for larger problems. Now I'm trying to translate an iterative function written in python to java so that I can analyze each subset as it's created and get only the value that represents how optimized it is and not the entire set so that I won't run out of memory. Here is what I have so far and it doesn't seem to finish even for very small problems: public static LinkedList<LinkedList<Integer>>

I need to get all possible subsets of an array. Say I have this: [1, 2, 3] How do I get this? [], [1], [2], [1, 2], [2, 3], [1, 3], [1, 2, 3] I am interested in all subsets. For subsets of specific length, refer to the following questions: Finding subsets of size n: 1 , 2 Finding subsets of size > 1: 1 Here is one more very elegant solution with no loops or recursion, only using the map and reduce array native functions. const getAllSubsets = theArray => theArray.reduce( (subsets, value) => subsets.concat( subsets.map(set => [value,...set]) ), [[]] ); console.log(getAllSubsets([1,2,3])); We

If I want to select a subset of data in R, I can use the subset function. I wanted to base an analysis on data that that was matching one of a few criteria, e.g. that a certain variable was either 1, 2 or 3. I tried myNewDataFrame <- subset(bigfive, subset = (bigfive$bf11==(1||2||3))) It did always just select values that matched the first of the criteria, here 1. My assumption was that it would start with 1 and if it does evaluate to "false" it would go on to 2 and than to 3, and if none matches the statement after == is "false" and if one of them matches, it is "true". I got the right result

I have a dataset called EPL2011_12 . I would like to make new a dataset by subsetting the original by date. The dates are in the column named Date The dates are in DD-MM-YY format. I have tried EPL2011_12FirstHalf <- subset(EPL2011_12, Date > 13-01-12) and EPL2011_12FirstHalf <- subset(EPL2011_12, Date > "13-01-12") but get this error message each time. Warning message: In Ops.factor(Date, 13- 1 - 12) : > not meaningful for factors I guess that means R is treating like text instead of a number and that why it won't work? Well, it's clearly not a number since it has dashes in it. The error

I'm familiar with being able to extract columns from an R data frame (or matrix) like so: df.2 <- df[, c("name1", "name2", "name3")] But can one use a ! or other tool to select all but those listed columns ? For background, I have a data frame with quite a few column vectors and I'd like to avoid: Typing out the majority of the names when I could just remove a minority Using the much shorter df.2 <- df[, c(1,3,5)] because when my .csv file changes, my code goes to heck since the numbering isn't the same anymore. I'm new to R and think I've learned the hard way not to use number vectors for

Why doesn't subset() work with a logical and && operator combining two conditions? > subset(tt, (customer_id==177 && visit_date=="2010-08-26")) <0 rows> (or 0-length row.names) but they each work individually: > subset(tt, customer_id==177) > subset(tt, visit_date=="2010-08-26") (Want to avoid using large temporary variables - my dataset is huge) From the help page for Logical Operators , accessible by ?"&&" : & and && indicate logical AND and | and || indicate logical OR. The shorter form performs elementwise comparisons in much the same way as arithmetic operators. The longer form evaluates