循环访问R中的列表的for循环内的if循环? [英] if loop inside a for loop which iterates over a list in R?

问题描述

使用R完成了初学者的学习，我环顾了四周，但找不到所需的东西.

Complete beginner with R and I've looked around quite a bit but I can't find what I need.

我有一个for循环，它循环访问值列表.我想在该for循环中放入一个if循环，如下所示:

I have a for loop which iterates over a list of values. I want to put an if loop within that for loop, like this:

    for (i in list){
    if (i>200){
        print (i)
        }
    }

这将返回以下警告:

"警告消息: 如果(i> 200){: 条件的长度> 1，并且只会使用第一个元素.

"Warning message: In if (i > 200) { : the condition has length > 1 and only the first element will be used"

可以肯定的是，if循环仅检查列表中第一个元素的条件.

and sure enough, the if loop only checks the condition on the very first element in the list.

我知道这可能是因为for循环在R中未返回任何内容，但是解决方法是什么.我该如何解决?

I understand that this might be because the for loops don't return anything in R, but what's the workaround. How do I solve this?

感谢您的帮助.

推荐答案

for (i in 1:20){
     if (i>10) print(i)
    }

通常，条件为true或false:1或0.因此条件必须始终为1.

In general, conditions are either true or false: 1 or 0. So the condition must always have length 1.

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