替换与多个不同模式匹配的列值

debugcn 发表于 Dev

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在以下数据框中：

library(tidyverse)
df <- tibble(notes=c("Positive result","Negative","NEG","POS >2","pOS","Cannot Determine","2.4","3.1","0.2"))

  notes           
  <chr>           
1 Positive result 
2 Negative        
3 NEG             
4 POS >2          
5 pOS             
6 Cannot Determine
7 2.4             
8 3.1             
9 0.2

我想定义一个单行来替换注释列中与模式匹配的条目。如果只有两个条件，我会使用三元运算符。但是这里有5个

我正在尝试将注释中的值替换为：

could be turned into a double -> "3"
grepl("pos",tolower(notes)) -> "2"
grepl("neg",tolower(notes)) -> "1"
以上都不是-> "0"

我最初是这样做的：

df %>%
  mutate(notes=ifelse(grepl("[[:digit:]]+",notes)),"3",notes) %>%  # could be coerced into a double
  mutate(notes=ifelse(grepl("pos",tolower(notes))),"2",notes) %>%  # contains "pos"
  mutate(notes=ifelse(grepl("neg",tolower(notes))),"1",notes) %>%  # contains "neg"
  mutate(notes=ifelse(grepl("3|2|1",tolower(notes))),notes,"0") %>%  # none of the above
  type.convert()

期望的输出

阿克伦

我们可以用 case_when

library(dplyr)
library(stringr)
df %>% 
  mutate(notes1 = toupper(substr(notes, 1, 3)), 
        notes =case_when(notes1 == "POS" ~ 2, 
                         notes1 == 'NEG' ~ 1, 
                         str_detect(notes, '^[0-9.]+$')~ 3,
                         TRUE ~ 0)) %>%
  select(-notes1)
# A tibble: 9 x 1
#  notes
#  <dbl>
#1     2
#2     1
#3     1
#4     2
#5     2
#6     0
#7     3
#8     3
#9     3

如果我们需要保持数值不变，则一个选项是as.numeric然后coalesce

df %>% 
 mutate(notes1 = toupper(substr(notes, 1, 3)), 
      notes2 =case_when(notes1 == "POS" ~ 2, 
                       notes1 == 'NEG' ~ 1, 
                       str_detect(notes, '^[0-9.]+$')~ 3,
                       TRUE ~ 0)) %>%
 select(-notes1) %>% 
 mutate(notes = coalesce(as.numeric(notes), notes2)) %>% 
 select(-notes2)

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