格式化R中的小数位 [英] Formatting Decimal places in R
问题描述
我有一个数字,例如1.128347132904321674821,当输出到屏幕(或写入文件)时,我想只显示两位小数。一个人怎么做?
x < - 1.128347132904321674821
编辑:
使用:
options(digits = 2)
已被建议作为可能的答案。有一种方法可以在脚本中指定一次性使用吗?当我将它添加到我的脚本中时,它似乎没有做任何不同的事情,我不想重新输入格式化每个数字(我自动化一个非常大的报告)。
< - > -
回答:round(x,digits = 2)
背景:在此页面上建议的一些答案(例如 signif
options(digits = ...)
)不保证显示任意数字的小数位数。我认为这是R中的一个设计特征,其中良好的科学实践涉及根据原则显示一定数量的数字有效数字。然而,在许多领域(例如, APA风格,业务报告)格式化要求规定显示一定数量的小数位数。这通常是为了一致性和标准化的目的,而不是关注重要数字。
解决方案:
下面的代码显示了数字 x
的精确到位的两位小数。
格式(round(x,2),nsmall = 2)
:
$ p $ format(round(1.20,2),nsmall = 2)
#[1]1.20
格式(round(1,2),nsmall = 2)
#[1]1.00
格式(round(1.1234,2),nsmall = 2)
# 1]1.12
更一般的函数如下所示,其中 x
是数字, k
是显示的小数位数。 trimws
删除任何前导空格,如果您有一个向量的数字,那么这个空格是有用的。
specify_decimal < - function(x,k)trimws(format(round(x,k),nsmall = k))
例如,
specify_decimal(1234,5)
#[1] 1234.00000
specify_decimal(0.1234,5)
#[1]0.12340
I have a number, for example 1.128347132904321674821 that I would like to show as only two decimal places when output to screen (or written to a file). How does one do that?
x <- 1.128347132904321674821
EDIT:
The use of:
options(digits=2)
Has been suggested as a possible answer. Is there a way to specify this within a script for one-time use? When I add it to my script it doesn't seem to do anything different and I'm not interested in a lot of re-typing to format each number (I'm automating a very large report).
--
Answer: round(x, digits=2)
Background: Some answers suggested on this page (e.g., signif
, options(digits=...)
) do not guarantee that a certain number of decimals are displayed for an arbitrary number. I presume this is a design feature in R whereby good scientific practice involves showing a certain number of digits based on principles of "significant figures". However, in many domains (e.g., APA style, business reports) formatting requirements dictate that a certain number of decimal places are displayed. This is often done for consistency and standardisation purposes rather than being concerned with significant figures.
Solution:
The following code shows exactly two decimal places for the number x
.
format(round(x, 2), nsmall = 2)
For example:
format(round(1.20, 2), nsmall = 2)
# [1] "1.20"
format(round(1, 2), nsmall = 2)
# [1] "1.00"
format(round(1.1234, 2), nsmall = 2)
# [1] "1.12"
A more general function is as follows where x
is the number and k
is the number of decimals to show. trimws
removes any leading white space which can be useful if you have a vector of numbers.
specify_decimal <- function(x, k) trimws(format(round(x, k), nsmall=k))
E.g.,
specify_decimal(1234, 5)
# [1] "1234.00000"
specify_decimal(0.1234, 5)
# [1] "0.12340"
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