# pick-methods: Extract a Single Result from a List In planor: Generation of Regular Factorial Designs

## Description

Methods to extract a single `designkey` object (with one key matrix per prime) from a multi-components object.

## Usage

 ```1 2 3 4``` ```## S4 method for signature 'listofdesignkeys' pick(keys, selection) ## S4 method for signature 'listofkeyrings' pick(keys, selection) ```

## Arguments

 `keys` an object of the class. `selection` when `keys` is a `listofdesignkeys` object, an integer scalar equal to the position of the required solution. when `keys` is a `listofkeyrings` object, the index vector to select the key matrix for each prime.

## Value

An object of class `designkey`, which contains the selected design.

## Note

`pick(K0,1)` can be simply written `K0`

Classes where this method applies: `listofdesignkeys`, `listofkeyrings`.
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15``` ```### Creation of an object of class listofdesignkeys K2 <- planor.designkey(factors=c("R","C","U","A","B1","B2"), nlevels=c(3,2,2,3,2,2), model=~R*C + (A+B1+B2)^2, estimate=~A:B1+A:B2 , nunits=12, base=~R+C+U, max.sol=2) ### Method pick applied on the listofdesignkeys object K2.1 <- pick(K2,1) K2.1 <- K2 ## Another way of extracting ([ is synonym of pick) ### Creation of an object of class listofkeyrings K0 <- planor.designkey(factors=c(LETTERS[1:4], "block"), nlevels=rep(3,5), model=~block+(A+B+C+D)^2, estimate=~A+B+C+D, nunits=3^3, base=~A+B+C, max.sol=2) ### Method pick applied on the listofkeyrings object K0.1 <- pick(K0,1) K0.1 <- K0 ## the same ```