我可以制作一个函数来使用循环制作这样的数据框吗?(后续问题) [英] Can I make a function that makes a dataframe like this using loops? (follow up question)

问题描述

感谢您对此问题的关注.

Thank you for your interest in this question.

我有如下数据.

a<- data.frame("Grade"=c(1, 2, 3, 4), "Prob"=c(0.01, 0.25, 0.45, 0.29))
b<- data.frame("Pot"= c(letters[1:18]))

基于下面的代码，我想制作一个函数，该函数可以根据概率(replace=TRUE)和四个相同概率的随机字母(replace=FALSE)循环 4 个成绩数字.例如，这个循环可能如下所示:

Based on the codes below, I'd like to make a function that can loop 4 Grade numbers based on the Prob probability (replace=TRUE) and four random letters with the same probability (replace=FALSE). For instance, this loop may look like below:

3 2 3 2 d f k g
1 3 4 2 a k r b 

我想做一个函数，它不仅可以计算成绩结果仅低于 3 的结果，以及我选择的四个字母出现的结果，还可以计算获得此结果的试验次数.所以，如果我想让 Pot 有a"、b"、c"和d"结果将如下所示:

I'd like to make a function that can compute not only the results in which the Grades result is only lower than 3, and the four alphabets that I selected appear, but the number of trials to get this result. So, if I want Pot to have "a", "b", "c", and "d" the result will look like:

 Trial Grade   Pot
15    3 2 1 3  a b c d
39    2 1 2 2  d b a c
2     3 3 3 3  d a b d
77    3 2 3 3  c d b a

感谢一位非常友善的人，我可以学习以下代码，但我无法对其进行编辑以获得我希望看到的结果.你能帮我吗?

I could learn the below code thanks to a very kind person, but I can't edit it to get the results I hope to see. Can you please help me?

     samplefun <- function(a) {
      c <- sample(a$Grade, size=4, prob=a$Prob, replace=TRUE)
      
      res <- tibble(
        Trial = which(c < 3)[1],
        Result = c[which(c < 3)[1]]
      )
nsamples <- 1000
x<-map_dfr(1:nsamples, ~ samplefun(a))

感谢您阅读这个问题.

推荐答案

这是我认为您所追求的解决方案.我在采样 b$Pot 时没有指定概率向量，因为你没有在你的问题中给出一个长度为 18 个元素的概率向量(见我的评论).

Here's a solution to what I think you're after. I haven't specified a probability vector when sampling b$Pot, because you didn't give one that was 18 elements long in your question (see my comment).

library(tidyverse)

a<- data.frame(Grade =c(1, 2, 3, 4), Prob = c(0.01, 0.25, 0.45, 0.29))
b<- data.frame(Pot = letters[1:18])

chosenletters <- c("a", "b", "c", "d")

samplefun <- function(a, b, chosenletters) {
  ntrials <- 0
  
  repeat {
    grades <- sample(a$Grade, size = 4, prob = a$Prob, replace = T)
    chars <- sample(b$Pot, size = 4, replace = F)
    ntrials <- ntrials + 1
    
    if (all(grades < 4) & all(chars %in% chosenletters)) {break}
  }
  
  return( tibble(Trial = ntrials, Grade = list(grades), Letters = list(chars)) )
}

nsamples <- 5
res <- map_dfr(1:nsamples, ~ samplefun(a, b, chosenletters))

这个数据框 res 给出了嵌入在每个数据框单元格内的列表中的正确等级和字母，以及生成结果的试验.

This dataframe res gives the correct Grades and Letters embedded in lists inside each dataframe cell, plus the trial at which the result was generated.

# A tibble: 5 x 3
  Trial Grade     Letters  
  <dbl> <list>    <list>   
1 20863 <dbl [4]> <fct [4]>
2  8755 <dbl [4]> <fct [4]>
3 15129 <dbl [4]> <fct [4]>
4  1033 <dbl [4]> <fct [4]>
5  5264 <dbl [4]> <fct [4]>

更好地查看嵌套列表:

> glimpse(res)
Rows: 5
Columns: 3
$ Trial   <dbl> 20863, 8755, 15129, 1033, 5264
$ Grade   <list> <3, 3, 3, 3>, <3, 2, 2, 2>, <3, 3, 2, 2>, <3, 3, 2, 3>, <3, 2, 3, 3>
$ Letters <list> <b, a, c, d>, <b, a, c, d>, <c, a, b, d>, <b, d, c, a>, <a, b, d, c>

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