I can actually answer this!! It will output a vector or a matrix (depending on the output of your function). tapply Function. Requires explanation, doesn’t it? Value. A list, or for SIMPLIFY = TRUE, a vector, array or list. tapply: Apply a Function Over a Ragged Array Description Usage Arguments Details Value Note References See Also Examples Description. or user-defined function. You use tapply() to create tabular summaries of data. outer, which applies a vectorized function to all combinations of two arguments. (2 replies) Dear list, I have the function (as a simple example, which is actually part of a larger function) pres.test<-function(N0=N0, N1=N1) { dt<-5 r<-log(N1/N0)/dt r } which calculates the annual growth rates in a population Where N0 is the population classified into age intervals, say 5 years, at time 95, and N1 is the population by 5 year age classes at time 00. Basically, tapply() applies a function or operation on subset of the vector broken down by a given factor variable. Value. R. Michael Weylandt There's a slight variant that might be even more helpful if you need to line the data up with how you started: ave(). However, table() can create only contingency tables (that is, tables of counts), whereas with tapply() you can specify any function as the aggregation function. You can use tapply to do some quick summary statistics on a variable split by condition. To understand clearly lets imagine you have height of 1000 people ( 500 male and 500 females), and you want to know the average height … sapply, after which mapply() is modelled. MARGIN. Examples So here’s how it goes – the first argument is the function FUN. x and y both have two values so the function is called twice. I'll let you work out the details, but the key difference is that it returns a vector that has the 90th percentile for each group, each time that group appears, instead of the summary table that you'd get from tapply() Michael On Tue, Nov … Apply a function to each cell of a ragged array, that is to each (non-empty) group of values given by a unique … Arguments with classes in ... will be accepted, and their subsetting and length methods will be used. Arguments with classes in ... will be accepted, and their subsetting and length methods will be used. Arguments X. an array, including a matrix. I was trying to figure out how to use sapply for a function I wrote with multiple arguments. outer, which applies a vectorized function to all combinations of two arguments. A list, or for SIMPLIFY = TRUE, a vector, array or list. Where X has named dimnames, it can be a character vector selecting dimension names.. FUN a vector giving the subscripts which the function will be applied over. E.g., for a matrix 1 indicates rows, 2 indicates columns, c(1, 2) indicates rows and columns. It takes in two parameters x and y. Suppose the function is called FUN(a,b), where "a" is a number and "b" is a number You can use mapply(FUN, a = VECTOR, b = VECTOR) where each vector is your input arguments. See Also. This is a little bit similar to the table() function. Each of the apply functions requires a minimum of two arguments: an object and another function. 4.0.2 Example 2: Combining functions. See Also. In this example, I created a function that returns a vector ofboth the mean and standard deviation. sapply, after which mapply() is modelled. The function can be any inbuilt (like mean, sum, max etc.) ... tapply() function. You can create a function like this for any apply function, not just tapply. The values of x come from the second argument (x=c(2,3)) and the values of y come from the 3rd argument (y=c(3,4)). tapply() is used to apply a function over subsets of a vector. 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