You can use the unlist()В to flatten the list and produce a simple vector. Example > lapply(list(1:5,20:26),median)ДЄs you can see, the lapply()В function returns a list (always).

It applies the given function to all elements of the specified list. The analog of apply()В for lists is lapply(). There are other functions which can be applied to lists and vectors. The applyВ function can be used with matrixes, arrays, and data frames. The following two examples show row minima and column maxima: > apply(myMatrix,1,min) #row minima We can do the same column-wise by changing MARGIN=2, as shown below: > apply(myMatrix,2,sum) The applyВ function applied the function sumВ to each row (specified with MARGIN=1) of the matrix myMatrix.

Now let's take a few examples to understand how we can use the apply()В function.Д¬alculate the sumВ of each row. For example, we can generate 30 Poisson random numbers with parameter О» = 3 as follows: > rpois(30, 3) > myMatrix myMatrix The rpois()В function is a built-in function that can be used to simulate N independent Poisson random variables. Let's define a simple matrix myMatrixВ which we will use to understand the apply()В function. represents additional arguments to the function FUN is the function to apply (example: mean()).MARGIN is the dimension number (1 = rows, 2 = columns).X is any R structure with dimensions (matrix, data frame, array.The apply()В function has the following structure: > args(apply)

The apply()В function applies a simple function over dimensions of a data structure. If speed is an issue, such as when working with large data sets or long-running simulations, one must avoid explicit loops (read 'for' loop, or 'while' loop) as much as possible, because with apply()В function and its variants, R can do them a lot faster than you can. The applyВ functions are not just for compactness of code, but also for speed. It is a whole family of functions that are commonly referred to as 'Apply' family of functions. R also provides other functions for implicit looping such as apply, lapplyВ and sapplyВ which are even easier to use. In the earlier lessons, we learned about how we can use the forВ loop to iterate over various R objects.

Lapply loop in r