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# Apply a Function over a Ragged Array in R Programming – tapply() Function

`tapply()` function in R Language is used to apply a function over a subset of vectors given by a combination of factors

Syntax: tapply(vector, factor, fun)

Parameters:
vector: Created Vector
factor: Created Factor
fun: Function to be applied

Example 1:

 `# R Program to apply a function``# over a data object`` ` `# Creating Factor``fac <``-` `c(``1``, ``1``, ``1``, ``1``, ``2``, ``2``, ``2``, ``3``, ``3``)`` ` `# Created Vector``vec <``-` `c(``1``, ``2``, ``3``, ``4``, ``5``, ``6``, ``7``, ``8``, ``9``) `` ` `# Calling tapply() Function``tapply(vec, fac, ``sum``)`

Output:

``` 1  2  3
10 18 17
```

This is how above code works:

Example 2:

 `# R Program to apply a function``# over a data object`` ` `# Creating Factor``fac <``-` `c(``1``, ``1``, ``1``, ``1``, ``2``, ``2``, ``2``, ``3``, ``3``)`` ` `# Created Vector``vec <``-` `c(``1``, ``2``, ``3``, ``4``, ``5``, ``6``, ``7``, ``8``, ``9``) `` ` `# Calling tapply() Function``tapply(vec, fac, prod)`

Output:

``` 1   2   3
24 210  72
```