如何在for循环中使用mutate()和case_when()? [英] How can I use mutate() and case_when() in a for loop?

问题描述

我正在编写一个Shiny应用程序，用户将在其中输入样品条件的数据，脚本将自动"将其输入条件与给定文件的样品名称匹配.

I'm writing a Shiny app where the user will be inputting data for conditions of their samples, and the script will "automatically" match their inputted conditions to sample names of a given file.

为简单起见，我将不包含闪亮的代码，因为我仅在实际的R实现中苦苦挣扎.

For simplicity, I will not include the shiny code, because I am only struggling with the actual R implementation.

如果我已经知道潜在的状况，可以执行以下操作:

If I already know what the potential conditions are, I could do something like:

library(tidyverse)
x <- data.frame(Samples = c('Low1', 'Low2', 'High1', 'High2', 
                           'Ctrl1', 'Ctrl2'))

x <- x %>% mutate(Conditions = case_when(
           str_detect(Samples, fixed("low", ignore_case = T)) ~ "low",
           str_detect(Samples, fixed("high", ignore_case = T)) ~ "high",
           str_detect(Samples, fixed("ctrl", ignore_case = T)) ~ "ctrl"))

我会得到我想要的东西，像这样的数据框:

And I would get what I am looking for, a data frame like:

Samples    Conditions
   Low1           low
   Low2           low
  High1          high
  High2          high
  Ctrl1          ctrl
  Ctrl2          ctrl

但是，我想遍历潜在条件的向量并做类似的事情:

However, I want to loop through a vector of potential conditions and do something like:

library(tidyverse)
condition_options <- c('low', 'high', 'ctrl')

x <- data.frame(Samples = samplenames)
for (j in condition_options) {
   x <- x %>% mutate(Condition = case_when(
        str_detect(Samples, fixed(j, ignore_case = T)) ~ j)) 
    }

执行此操作时，仅重写Condition列，使我与向量中的最后一个值匹配.例如:

When I do this, the Condition column is re-written only giving me matches for the last value in the vector. For example:

Samples    Conditions
   Low1         <NA>
   Low2         <NA>
  High1         <NA>
  High2         <NA>
  Ctrl1         ctrl
  Ctrl2         ctrl

推荐答案

如果使用元编程而不是循环来构建case_when语句的所有部分，则可能会更容易.试试

This might be easier if you build all parts of your case_when statement with meta-programming rather than doing a loop. Try

library(tidyverse)
condition_options <- c('low', 'high', 'ctrl')

conditions <- purrr::map(condition_options, 
                         ~quo(str_detect(Samples, fixed(!!.x, ignore_case = T))~!!.x))

x <- data.frame(Samples = samplenames)
x %>% mutate(Condition = case_when(!!!conditions) )

#   Samples Condition
# 1    Low1       low
# 2    Low2       low
# 3   High1      high
# 4   High2      high
# 5   Ctrl1      ctrl
# 6   Ctrl2      ctrl

在这里map构建您希望在case_when语句中拥有的所有不同公式.然后，我们使用!!!将其插入mutate表达式中.

Here the map build all the different formulas you would expect to have in the case_when statement. Then we use !!! to insert them into the mutate expression.

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