查看数据帧的内容时是否可以截断输出？ [英] Is it possible to truncate output when viewing the contents of dataframes?

问题描述

我有一个带有一些很长的注释列的数据框。当我显示它们时，它们分为不同的块，这使得跨行读取变得困难。是否可以更改R中的设置或修改对data.frame的调用以截断特定长度的字符串？

I have a data frame with some very long "comments" columns. When I have them displayed they are broken into different blocks, making it hard to read across rows. Is it possible to change a setting in R or modify the call to data.frame to truncate strings at a certain length?

例如：3列数据框

Example: a 3-column dataframe

data.frame(cbind(rep(1,5),rep(c("very very long obnoxious character string here" ,"dog","cat","dog",5)),rep(c("very very long obnoxious character string here" ,"dog","cat","dog",5))))

在我的屏幕上看到的结果数据帧：

Resulting dataframe as seen on my screen:

  X1                                             X2
1  1 very very long obnoxious character string here
2  1                                            dog
3  1                                            cat
4  1                                            dog
5  1                                              5
                                          X3
1 very very long obnoxious character string here
2                                            dog
3                                            cat
4                                            dog
5                                              5

推荐答案

我推荐一种类似这样的显式方式：

I recommend a kind of the explicit way like this:

f <- function(x) data.frame(lapply(x, substr, 1, 5))

用法：

> f(d)
  X1    X2    X3
1  1 very  very 
2  1   dog   dog
3  1   cat   cat
4  1   dog   dog
5  1     5     5

尽管可以更改默认行为，但我不建议：

Although it is possible to change the default behavior, I don't recommend:

body(format.data.frame)[[5]] <- quote(for (i in 1L:nc) rval[[i]] <- substr(format(x[[i]], ..., justify = justify), 1, 5))
unlockBinding("format.data.frame", baseenv())
assign("format.data.frame", format.data.frame, pos = baseenv())
lockBinding("format.data.frame", baseenv())
rm(format.data.frame)

使用情况：

> d
  X1    X2    X3
1  1 very  very 
2  1   dog   dog
3  1   cat   cat
4  1   dog   dog
5  1     5     5

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