R readr :: read_fwf使用fwf_widths忽略字符 [英] R readr::read_fwf ignore characters using fwf_widths

问题描述

我想知道是否有一种简单的方法可以使用R中的readr包中的read_fwf来跳过字符.

I would like to know if there is an easy way to skip characters using the read_fwf from the readr package in R.

例如，修改文档中的示例之一

For example, modifying one of the examples in the documentation

library(readr)
fwf_sample <- system.file("extdata/fwf-sample.txt", package = "readr")
read_fwf(fwf_sample, fwf_widths(c(2, -3,2, 3)))

引发错误:

Error: Begin offset (2) must be smaller than end offset (-1)

使用基本的read.fwf函数可以很好地工作:

Using the base read.fwf function works just fine however:

read.fwf(fwf_sample, widths = c(2,-3,2,3))

#  V1 V2  V3
#1 12 67 890
#2 12 67 890
#3 12 67 890
#4 12 67 890
#5 12 67 890

是否可以使用readr::read_fwf模仿此行为? (我主要是出于性能方面的考虑).

Is there a way I can mimic this behaviour using readr::read_fwf? (I am interested mostly for performance reason).

推荐答案

帮助页面建议使用fwf_positions:

> read_fwf(fwf_sample, fwf_positions(c(1, 5, 8), c(2, 7, 10),  col_names=paste0("V", 1:3)) )
Parsed with column specification:
cols(
  V1 = col_character(),
  V2 = col_character(),
  V3 = col_character()
)
# A tibble: 3 x 3
     V1    V2    V3
  <chr> <chr> <chr>
1    Jo    Sm   ith
2    Ma    Ha   rtf
3    Ev    No   lan

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