英文:
How to generate a random integers vector that sums up to a given number in R
问题
我有一个名为my_df的数据框，我想要添加一个额外的列，名为my_new_column，并用随机整数填充，使它们相加等于给定的总和。以下是一些可重复的代码：
library(dplyr)
library(magrittr)
my_df <- as.data.frame(matrix(nrow = 10, ncol = 2))
colnames(my_df) <- c("Cat", "MarksA")
my_df$Cat <- LETTERS[1:nrow(my_df)]
my_df$MarksA <- sample(1:100, size = nrow(my_df))
在Tidyverse 风格中，我尝试了以下代码：
my_df %<>% mutate(my_new_column=sample(n()))
然而，这给我一个列，其总和是一个任意的数字。如何调整我的代码以实现这个任务？
英文:
I have a dataframe my_df and I would like to add an additional column, my_new_column, and populate it with random integer numbers that add up to a given sum.
Here is some reproducible code:
library(dplyr)
library(magrittr)
my_df <- as.data.frame(matrix(nrow = 10, ncol = 2))
colnames(my_df) <- c("Cat", "MarksA")
my_df$Cat <- LETTERS[1:nrow(my_df)]
my_df$MarksA <- sample(1:100, size = nrow(my_df))
In Tidyverse style, I tried the following:
my_df %<>% mutate(my_new_column=sample(n()))
However, this gives me a column which sums up to an arbitrary number. How can I tweak my code to achieve this task?
答案1
得分: 3
由于您没有指定特定的分布，这个方法适用吗？我主要从这篇帖子中提取了我的答案，其中包含更多详细信息和更多选项：https://stackoverflow.com/questions/52559455/generate-non-negative-or-positive-random-integers-that-sum-to-a-fixed-value
my_df %>%
mutate(int_sample = rmultinom(n = 1, size = 1000, prob = rep.int(1 / 10, 10)))
英文:
Since you didn't specify a specific distribution, would this work? I pulled my answer mostly from this post which has more details and more options: https://stackoverflow.com/questions/52559455/generate-non-negative-or-positive-random-integers-that-sum-to-a-fixed-value
my_df %>%
mutate(int_sample = rmultinom(n = 1, size = 1000, prob = rep.int(1 / 10, 10)))
答案2
得分: 0
Since the sum of all numbers between 1 and n is equal to n(n + 1)/2, you may try something like this:
nb <- nrow(my_df)
my_df %<>% mutate(my_new_column = sample(nb * (nb + 1)/2))
英文:
Since the sum of all numbers between 1 and n is equal to n(n + 1)/2, you may try something like this :
nb <- nrow(my_df)
my_df %<>% mutate(my_new_column = sample(nb * (nb + 1)/2))
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