• Sorting Program In Java
• Data Sorting Program

You can use the function directly without resorting to add-on tools - see this simpler answer which uses a trick right from the top of the example(order) code: R ddwith(dd, order(-z, b))b x y z 4 Low C 9 2 2 Med D 3 1 1 Hi A 8 1 3 Hi A 9 1 Edit some 2+ years later: It was just asked how to do this by column index. The answer is to simply pass the desired sorting column(s) to the order function: R dd order(-dd,4, dd,1)b x y z 4 Low C 9 2 2 Med D 3 1 1 Hi A 8 1 3 Hi A 9 1 R rather than using the name of the column (and with for easier/more direct access). Dirk's answer is great. It also highlights a key difference in the syntax used for indexing data.frames and data.tables: ## The data.frame way ddwith(dd, order(-z, b))## The data.table way: (7 fewer characters, but that's not the important bit) ddorder(-z, b) The difference between the two calls is small, but it can have important consequences. Especially if you write production code and/or are concerned with correctness in your research, it's best to avoid unnecessary repetition of variable names. Data.table helps you do this.

Here's an example of how repetition of variable names might get you into trouble: Let's change the context from Dirk's answer, and say this is part of a bigger project where there are a lot of object names and they are long and meaningful; instead of dd it's called quarterlyreport. It becomes: quarterlyreportwith(quarterlyreport,order(-z,b)), Ok, fine. Nothing wrong with that. Next your boss asks you to include last quarter's report in the report. You go through your code, adding an object lastquarterlyreport in various places and somehow (how on earth?) you end up with this: quarterlyreportwith(lastquarterlyreport,order(-z,b)), That isn't what you meant but you didn't spot it because you did it fast and it's nestled on a page of similar code. The code doesn't fall over (no warning and no error) because R thinks it is what you meant. You'd hope whoever reads your report spots it, but maybe they don't.

If you work with programming languages a lot then this situation may be all to familiar. It was a 'typo' you'll say.

Sorting Program In Java

I'll fix the 'typo' you'll say to your boss. In we're concerned about tiny details like this. So we've done something simple to avoid typing variable names twice. Something very simple.

I is evaluated within the frame of dd already, automatically. You don't need with at all.

Data Sorting Program

Examples of sorting files on an IBM Mainframe System using the ZOS SORT program or on a Linux. Mainframe JCL for ZOS SORT. Set MIFOEDEV=C: Program Files. Sorting Data. To sort a data frame in R, use the order( ) function. By default, sorting is ASCENDING. Prepend the sorting variable by a minus sign to indicate. C Program to Frame sorting technique used in buffers. How to write a C Program to Frame sorting technique used in buffers in C Programming Language?

Instead of ddwith(dd, order(-z, b))it's just ddorder(-z, b) And instead of quarterlyreportwith(lastquarterlyreport,order(-z,b)), it's just quarterlyreportorder(-z,b) It's a very small difference, but it might just save your neck one day. When weighing up the different answers to this question, consider counting the repetitions of variable names as one of your criteria in deciding. Some answers have quite a few repeats, others have none.

The R package data.table provides both fast and memory efficient ordering of data.tables with a straightforward syntax (a part of which Matt has highlighted quite nicely ). There has been quite a lot of improvements and also a new function setorder since then. From v1.9.5+, setorder also works with data.frames. First, we'll create a dataset big enough and benchmark the different methods mentioned from other answers and then list the features of data.table.

Data: require(plyr) require(doBy) require(data.table) require(dplyr) require(taRifx) set.seed(45L) dat = data.frame(b = as.factor(sample(c('Hi', 'Med', 'Low'), 1e8, TRUE)), x = sample(c('A', 'D', 'C'), 1e8, TRUE), y = sample(100, 1e8, TRUE), z = sample(5, 1e8, TRUE), stringsAsFactors = FALSE) Benchmarks: The timings reported are from running system.time(.) on these functions shown below. The timings are tabulated below (in the order of slowest to fastest). I learned about order with the following example which then confused me for a long time: set.seed(1234) ID = 1:10 Age = round(rnorm(10, 50, 1)) diag = c('Depression', 'Bipolar') Diagnosis = sample(diag, 10, replace=TRUE) data = data.frame(ID, Age, Diagnosis) databyAge = dataorder(Age), databyAge The only reason this example works is because order is sorting by the vector Age, not by the column named Age in the data frame data.

To see this create an identical data frame using read.table with slightly different column names and without making use of any of the above vectors: my.data.

This is possibly a simple question, but I do not know how to order columns alphabetically. Test = data.frame(C = c(0, 2, 4, 7, 8), A = c(4, 2, 4, 7, 8), B = c(1, 3, 8, 3, 2)) # C A B # 1 0 4 1 # 2 2 2 3 # 3 4 4 8 # 4 7 7 3 # 5 8 8 2 I like to order the columns by column names alphabetically, to achieve # A B C # 1 4 1 0 # 2 2 3 2 # 3 4 8 4 # 4 7 3 7 # 5 8 2 8 For others I want my own defined order: # B A C # 1 4 1 0 # 2 2 3 2 # 3 4 8 4 # 4 7 3 7 # 5 8 2 8 Please note that my datasets are huge, with 10000 variables. So the process needs to be more automated. You can use order on the names, and use that to order the columns when subsetting: test, order(names(test)) A B C 1 4 1 0 2 2 3 2 3 4 8 4 4 7 3 7 5 8 2 8 For your own defined order, you will need to define your own mapping of the names to the ordering. This would depend on how you would like to do this, but swapping whatever function would to this with order above should give your desired output. You may for example have a look at, i.e. You can match your data frame names against a target vector containing the desired column order.