限制数据帧(R)中的小数位数 [英] Limiting the number of decimals in a dataframe (R)

问题描述

我想限制导入数据帧时的小数位数.我的.txt输入在值"列的每一行都有16个小数.我的数据框看起来像这样:

I would like to limit the number of decimals when a data frame is imported. My .txt input have 16 decimals to each row in collumn "Value". My dataframe look like that:

Value 

0.202021561664556
0.202021561664556
0.202021561664556
0.202021561664556
...

我期望的数据框

Value
0.20202156
0.20202156
0.20202156
0.20202156
...

无效的实际输入(DF):

Real input (DF) that not works:

DF <- "NE001358.Log.R.Ratio
    -0.0970369274475688
    0.131893549586039
    0.0629266495860389
    0.299559132381831
    -0.0128804337656807
    0.0639743960526874
    0.0271669351886552
    0.322395363972391
    0.179591292893632"

DF <- read.table(text=DF, header = TRUE)

推荐答案

对于数字列，此处 is.num 为 TRUE ，否则为 FALSE .然后，我们将 round 应用于数字列:

Here is.num is TRUE for numeric columns and FALSE otherwise. We then apply round to the numeric columns:

is.num <- sapply(DF, is.numeric)
DF[is.num] <- lapply(DF[is.num], round, 8)

如果您的意思不是您需要更改数据框，而是只想将数据框显示为8位数字，那么它就是:

If what you meant was not that you need to change the data frame but just that you want to display the data frame to 8 digits then it's just:

print(DF, digits = 8)

在dplyr 1.0.0及更高版本中，可以像这样在 mutate 中使用 across :

In dplyr 1.0.0 and later one can use across within mutate like this:

library(dplyr)
DF %>% mutate(across(is.numeric, ~ round(., 8)))

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