r - if/else 语句中的 str_split_fixed : unexpected results

Question

我的数据框中的数据格式为:

structure(list(O2Range = c("112 MAX", "16/19", "16/190", "12 MAX", 
NA, NA, NA, NA, NA, NA, NA, "16/20", "18/22", NA, "16/20", NA, 
"11/13", NA, "16/190", NA)), row.names = c(NA, -20L), class = c("tbl_df", 
"tbl", "data.frame"))

显而易见，低 O2 读数和高 O2 读数在列中用“/”分隔，但有时会先列出数字，然后列出“MAX”(即:112 MAX)。

我试图通过以下方式将此列分成两个新列:

library(tidyverse)
data$O2High <- if (str_detect(data$O2Range, "/")) {str_split_fixed(data$O2Range, fixed("/"), 2)[, 2]
} else {str_split_fixed(data$O2Range, fixed(" "), 2)[, 2]}
data$O2Low <- if (str_detect(data$O2Range, "/")) {str_split_fixed(data$O2Range, fixed("/"), 2)[, 1]
        } else {str_split_fixed(data$O2Range, fixed(" "), 2)[, 1]}

但是，结果并没有达到预期:

structure(list(O2High = c("MAX", "", "", "MAX", "", "", "", "", 
"", "", "", "", "", "", "", "", "", "", "", ""), O2Low = c("112", 
"16/19", "16/190", "12", "", "", "", "", "", "", "", "16/20", 
"18/22", "", "16/20", "", "11/13", "", "16/190", "")), row.names = c(NA, 
-20L), class = c("tbl_df", "tbl", "data.frame"))

我的 if/else 语句似乎出了问题，但我无法解决这个问题。有什么想法吗？

预期输出:

Expected output:

structure(list(O2High = list("112", "19", "190", "12", NA_character_, 
    NA_character_, NA_character_, NA_character_, NA_character_, 
    NA_character_, NA_character_, "20", "22", NA_character_, 
    "20", NA_character_, "13", NA_character_, "190", NA_character_), 
    O2Low = list("MAX", "16", "16", "MAX", NA_character_, 
        NA_character_, NA_character_, NA_character_, NA_character_, 
        NA_character_, NA_character_, "16", "18", NA_character_, 
        "16", NA_character_, "11", NA_character_, "16", NA_character_)), row.names = c(NA, 
-20L), class = c("tbl_df", "tbl", "data.frame"))

谢谢你， 克里斯

Answer 1

不确定如何处理 MAX，但是...

library(stringi)
as.data.frame(data) %>% 
     mutate(o2High = stri_extract_all_regex(O2Range, "(?<=/)[0-9]+"),
            o2Low = stri_extract_all_regex(O2Range, "[0-9]+(?=\\/)"))

   O2Range o2High o2Low
1  112 MAX     NA    NA
2    16/19     19    16
3   16/190    190    16
4   12 MAX     NA    NA
5     <NA>     NA    NA
6     <NA>     NA    NA
7     <NA>     NA    NA
8     <NA>     NA    NA
9     <NA>     NA    NA
10    <NA>     NA    NA
11    <NA>     NA    NA
12   16/20     20    16
13   18/22     22    18
14    <NA>     NA    NA
15   16/20     20    16
16    <NA>     NA    NA
17   11/13     13    11
18    <NA>     NA    NA
19  16/190    190    16
20    <NA>     NA    NA

或者

as.data.frame(df) %>% 
    mutate(
        o2High = stri_extract_all_regex(O2Range, "(?<=/)[0-9]+|[0-9]+(?=\\sMAX)"),
        o2Low = stri_extract_all_regex(O2Range, "[0-9]+(?=\\/)")
    )
   O2Range o2High o2Low
1  112 MAX    112    NA
2    16/19     19    16
3   16/190    190    16
4   12 MAX     12    NA
5     <NA>     NA    NA
6     <NA>     NA    NA
7     <NA>     NA    NA
8     <NA>     NA    NA
9     <NA>     NA    NA
10    <NA>     NA    NA
11    <NA>     NA    NA
12   16/20     20    16
13   18/22     22    18
14    <NA>     NA    NA
15   16/20     20    16
16    <NA>     NA    NA
17   11/13     13    11
18    <NA>     NA    NA
19  16/190    190    16
20    <NA>     NA    NA