r - 计算向量中x的元素个数(Counting the number of elements with the values of x in a vector)

Question

I have a vector of numbers:

(我有一个数字向量：)

numbers <- c(4,23,4,23,5,43,54,56,657,67,67,435,
         453,435,324,34,456,56,567,65,34,435)

How can I have R count the number of times a value x appears in the vector?

(如何让R计算向量中值x出现的次数？)

  ask by RQuestions translate from so

Answer 1

You can just use table() :

(您可以只使用table() ：)

> a <- table(numbers)
> a
numbers
  4   5  23  34  43  54  56  65  67 324 435 453 456 567 657 
  2   1   2   2   1   1   2   1   2   1   3   1   1   1   1 

Then you can subset it:

(然后，您可以将其子集化：)

> a[names(a)==435]
435 
  3

Or convert it into a data.frame if you're more comfortable working with that:

(或将其转换为data.frame（如果您更喜欢这样做）：)

> as.data.frame(table(numbers))
   numbers Freq
1        4    2
2        5    1
3       23    2
4       34    2
...