如何用R突变函数变换NA值?



我试图使用函数mutate是为了创建一个基于其他三个条件的变量。这些条件是使用case_when创建的,如下面的代码所示。

但是我有一些使用NA值的条件,这些似乎会导致mutate函数出错。请检查一下:

# About the variables being used:
unique(x1)
#   [1]  1  0 NA
str(pemg$x1)
# num [1:1622989] 1 0 0 1 1 0 1 1 0 0 ...
unique(x2)
#   [1]  16  66  38  11   8   6  14  17  53  59  10  31  50  19  48  42  44  21  54  55  56  18  57  61  13  43   7   4  15
#  [30]  39   5  20   3  37  23  51  36  52  68  58  27  65  62   2  12  32  41  49  46  35  34  45  81  69  33  40   0  70
#  [59]   9  47  63  29  25  22  64  24  60  30  67  26  71  72  28   1  75  80  87  77  73  78  76  79  74  83  92 102  85
#  [88]  86  90  82  91  84  88  93  89  96  95 105 115 106  94 100  99  97 104  98 103 108 109 101 117 107 114 113  NA 112
# [117] 110 111
str(pemg$x2)
# num [1:1622989] 16 66 38 11 8 6 14 17 53 59 ...
unique(x3)
#   [1]  6  3  4  5  0  8  2  1 11  9 10  7 NA 15
str(pemg$anoest)
# num [1:1622989] 6 3 4 5 3 0 5 8 4 2 ...
df <- mutate(df,
y = case_when(
x1 == 1 & x2 >=  7 & x3 ==  0 ~ 1,
x1 == 1 & x2 >=  8 & x3 ==  1 ~ 1,
x1 == 1 & x2 >= 10 & x3 ==  3 ~ 1,
x1 == 1 & x2 >= 11 & x3 ==  4 ~ 1,
x1 == 1 & x2 >= 12 & x3 ==  5 ~ 1,
x1 == 1 & x2 >= 13 & x3 ==  6 ~ 1,
x1 == 1 & x2 >= 14 & x3 ==  7 ~ 1,
x1 == 1 & x2 >= 15 & x3 ==  8 ~ 1,
x1 == 1 & x2 >= 16 & x3 ==  9 ~ 1,
x1 == 1 & x2 >= 17 & x3 == 10 ~ 1,
x1 == 1 & x2 >= 18 & x3 == 11 ~ 1,
x1 == 1 & !is.na(x3) ~ 0,
x1 == 1 & x3 %in% 12:16 ~ 0,
x2 %in% 0:7 ~ NA,
x2 > 18 ~ NA,
x1 == 0 ~ NA,
is.na(x3) ~ NA))
# Error: Problem with `mutate()` input `defasado`.
# x must be a double vector, not a logical vector.
# i Input `defasado` is `case_when(...)`.
# Run `rlang::last_error()` to see where the error occurred.
last_error()
# <error/dplyr_error>
# Problem with `mutate()` input `y`.
# x must be a double vector, not a logical vector.
# i Input `y` is `case_when(...)`.
# Backtrace:
#  1. dplyr::mutate(...)
#  2. dplyr:::mutate.data.frame(...)
#  3. dplyr:::mutate_cols(.data, ...)
#  Run `rlang::last_trace()` to see the full context.
last_trace()
# <error/dplyr_error>
# Problem with `mutate()` input `defasado`.
# x must be a double vector, not a logical vector.
# i Input `defasado` is `case_when(...)`.
# Backtrace:
#     x
#  1. +-dplyr::mutate(...)
#  2. -dplyr:::mutate.data.frame(...)
#  3.   -dplyr:::mutate_cols(.data, ...)
# <parent: error/rlang_error>
# must be a double vector, not a logical vector.
# Backtrace:
#     x
#  1. +-mask$eval_all_mutate(dots[[i]])
#  2. -dplyr::case_when(...)
#  3.   -dplyr:::replace_with(...)
#  4.     -dplyr:::check_type(val, x, name)
#  5.       -dplyr:::glubort(header, "must be {friendly_type_of(template)}, not {friendly_type_of(x)}.")
谁能给我一个提示,如何解决这个问题?

这里的问题是case_when的结果。if_else form dplyr比ifelse from base R更严格——所有结果值必须具有相同的类型。因为case_when是多个if_else的向量化,你必须告诉R输出应该是哪种NA类型:

library(dplyr)
# does not work
dplyr::tibble(d = c(6,2,4, NA, 5)) %>% 
dplyr::mutate(v = case_when(d < 4 ~ 0,
is.na(d) ~ NA))
# works
dplyr::tibble(d = c(6,2,4, NA, 5)) %>% 
dplyr::mutate(v = case_when(d < 4 ~ 0,
is.na(d) ~ NA_real_))

您需要确保您的NA's是正确的类。在您的情况下,将NA放在as.numeric()中的~之后。例如:

x2 %in% 0:7 ~ as.numeric(NA)

R有不同类型的NA。您正在使用的是逻辑类型,但是您需要双类型NA_real_,以便与其他条件的输出保持一致。欲了解更多信息,请参阅:https://stat.ethz.ch/R-manual/R-patched/library/base/html/NA.html

base R中,我们可以构造一个逻辑向量,并根据该逻辑向量将列值赋给NA。与case_when不同,我们不需要真正指定NA的类型,因为它会自动转换。

df1$d[df1$d %in% 0:7] <- NA

对于简单的操作,可以在base R中以紧凑的方式完成

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