将一列中的文本拆分为每一行的多列 [英] Splitting a text in one column into many columns for each row

问题描述

我有以下数据集:

Class      Range      Value
A          6 - 8      19
B          1 - 3      14
C          5 - 16     10
D          4 - 7      5

我想将每个班级的范围分成两列.为此，我使用了 str_split_fixed 函数，如下所示:

I want to split the range for each class into two columns. To do that, I used the function str_split_fixed as the following:

merge(data, str_split_fixed(data[, 2], " - ", 2))

我什至尝试过:

merge(data, str_split_fixed(data$Range, " - ", 2))

但他们都给了我以下结果:

But both of them give me the following results:

Class      Range      Value    V1     V2
A          6 - 8      19       6      8
B          1 - 3      14       6      8
C          5 - 16     10       6      8
D          4 - 7      5        6      8

我的问题是，为什么它会为其余课程重复第一个范围?有人可以帮忙吗?

My question is, why does it repeat the first range for the rest of the classes? Can someone help?

推荐答案

str_split_fixed 的输出是一个两列的matrix(没有dimnames)，当我们做一个merge 没有指定列名，它会进行交叉连接.代替 merge，我们可以使用 cbind 或分配给两列

The output of str_split_fixed is a two column matrix (no dimnames), and when we do a merge with out specifying the column name, it does a cross join. Instead of merge, we could use a cbind or assign to two columns

data[c('V1', 'V2')] <- str_split_fixed(data[, 2], " - ", 2)

注意:str_split 的输出是 character 类型的元素.它可能需要转换为 numeric

NOTE: The output of str_split are elements with character type. It may need to converted to numeric

更简单的选择是separate

library(tidyverse)
data %>%
    separate(Range, into = c("V1", "V2"), convert = TRUE)
#   Class V1 V2 Value
#1     A  6  8    19
#2     B  1  3    14
#3     C  5 16    10
#4     D  4  7     5

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