如何使用数据框中的值作为 R 中的 for 循环迭代器？

Question

我试图将数据框中的数值设置为 R 中 for 循环中的迭代器条件，但我无法让它工作。

脚本的思路是这样的：

遍历数据框中的行
对于每一行，根据行中的值指示循环遍历一个块

例如，我有一个名为 events 的数据框，如下所示：

Row     Event        Years
 1        1           10
 2        2           7

我想运行下面的循环来执行上面的脚本：

for (i in 1:nrow(events)){
  for(j in 1:events[i,2]{
    print(paste('The event number is',i,'and the year number is',j))
  }
}

我正在寻找的结果如下所示：

[1] "The event number is 1 and the year number is 1."
[1] "The event number is 1 and the year number is 2."
[1] "The event number is 1 and the year number is 3."
[1] "The event number is 1 and the year number is 4."
[1] "The event number is 1 and the year number is 5."
[1] "The event number is 1 and the year number is 6."
[1] "The event number is 1 and the year number is 7."
[1] "The event number is 1 and the year number is 8."
[1] "The event number is 1 and the year number is 9."
[1] "The event number is 1 and the year number is 10."
[1] "The event number is 2 and the year number is 1."
[1] "The event number is 2 and the year number is 2."
[1] "The event number is 2 and the year number is 4."
[1] "The event number is 2 and the year number is 5."
[1] "The event number is 2 and the year number is 6."
[1] "The event number is 2 and the year number is 7."

但我得到的结果是：

[1] "The event number is 1 and the year number is 1."
[1] "The event number is 2 and the year number is 1."
[1] "The event number is 2 and the year number is 2."

出于测试目的，我尝试了以下代码，它按我希望的方式工作...

for (i in 1:nrow(events)){
  for(j in 1:10){
    print(paste('The event number is',i,'and the year number is',j))
  }
}

...所以我尝试了各种方法来动态复制 10 值。

我是 R 新手，但我不是编程新手；我已经尝试了所有方法，从调用索引的方式到值的类型，再到使用 dim() 设置和获取维度，再到下面列出的其他方法：

1:as.numeric(events[i,2]
1:events$Years[i]
1:as.integer(events[i,2])
1:as.factor(events[i,2])

我认为我将迭代器视为单个值（如整数）而不是像因子或向量这样的 R 构造，这就是我遗漏的地方。我也读过有关使用 apply 函数解决此类问题的信息，但我不熟悉它的用法，所以我想先尝试解决 for 循环。

有谁知道我这里有什么问题吗？我一整天都在为这个烦恼！

在此先感谢您的帮助。

Answer 1

尝试：

df <- read.table(header = TRUE, text = "Row     Event        Years
1        1           10
2        2           7")

Count <- do.call("c", lapply(df$Years, function(x) seq(1, x)))
df <- df[rep(df$Event, df$Years) ,]
df <- cbind(df, Count)

paste("The event number is", df$Event, "and the year number is", df$Count)

我认为 for 循环不是一个好主意，如果你可以矢量化的话。

如何使用数据框中的值作为 R 中的 for 循环迭代器？

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