为什么 as.character 会去掉小数点？

Question

I'm interested to know why as.character(5.0) returns 5 but as.character(5.1) returns 5.1 in R. I tried to get an answer by reading the documentation but had no luck.

Answer 1

I'm interested to know why as.character(5.0) returns 5

The key word here is "returns ." What do you mean by that? Note that typing this in the console gives you 5:

> 5.0
[1] 5

5 is the same things as 5.0 for the purposes of calculation. So what you probably really care about is how 5 is printed . You thus need to use joran's method or a function like sprintf .

Answer 2

For more precise formatting of numbers as characters, you might use format :

> format(5,nsmall = 1)
[1] "5.0"