如何解决如何将purrr Modify_if与带有不同参数的多个函数一起使用？ 问题：
问题已解决！
问题：
在R中，我一直试图找到一种优雅的方法来将具有不同参数的多个函数应用于包含许多tibbles / data.frames的列表，但是，我一直在努力正确地传递参数。我正在尝试清洗和预处理药品中的文本数据，并且一直在尝试使用Modify_if，invoke，map等。任何帮助将不胜感激。
注意：只有开始学习编程，请原谅：）
# Set up Example Data
Test_DataFrame <- tibble("Integer_Variable" = c(rep(x = 1:4)),"Character_Variable" = c("tester to upper","test squishing","canitcomprehend?.,-0(`kljndsfiuhaweraeriou140987645=Error?"," test white space triming " ))
# With modify_if with a singular function and arguments it works:
# Mofidy character vectors by trimming the left side of the string --= works well
modify_if(.x = Test_DataFrame,.p = is.character,.f = str_trim,side = "left") # Works well
# Expected results
# A tibble: 4 x 2
# Integer_Variable Character_Variable
# <int> <chr>
# 1 1 "tester to upper"
# 2 2 "test squishing"
# 3 3 "canitcomprehend?.,-0(`kljndsfiuhaweraeriou140987645=Error?"
# 4 4 "test white space triming "
####### Note the right hanging whitespace proving the arguments is being applied!
但是，当我尝试使用一个以上带有任何参数的函数来执行此操作时，我遇到了麻烦（忽略函数参数）。我已经尝试了modify_if（下面有一些）和其他功能（例如，调用（但已停用），exec与map（对我而言毫无意义））的许多组合。到目前为止没有成功。非常感谢您的帮助。
# does not work
modify_if(.x = Test_DataFrame,.p = is.character # = the condition to specify which column to apply the functions to,.f = c( # a pairwise list of "name" = "function to apply" to apply to each column where the condition = TRUE
UpperCase = str_to_upper # Convert strings to upper case,TrimLeadTailWhiteSpace = str_trim # trim leading and ending whitespace,ExcessWhiteSpaceRemover = str_squish) # if you find any double or more whitespaces (eg " " or " ") then cut it down to " ",side = "left" # its ignoring these arguments.
)
# Does not work
modify_if(.x = Test_DataFrame,.f = c(UpperCase = list(str_to_upper) # listed variant doesnt work,TrimLeadTailWhiteSpace = list(str_trim,side = "left"),ExcessWhiteSpaceRemover = list(str_squish))
) # returns the integer variable instead of the character so drastically wrong
# Set up Function - Argument Table
Function_ArgumentList <- tibble("upper" = list(str_to_upper),"trim" = list(str_trim,"squish" = list(str_squish))
# Doesnt work
modify_if(.x = Test_DataFrame,.f = Function_ArgumentList)
# Error: Can't convert a `tbl_df/tbl/data.frame` object to function
# Run `rlang::last_error()` to see where the error occurred.
我意识到上面示例中使用的函数可以不带参数地传递，但是要解决我遇到的问题，这是我遇到的问题的简化示例。
解决方案：
感谢@stefan和@BenNorris的帮助；下面是p！ 为了更清楚地了解@stefan的解决方案，我对答案做了些微修改；
library(dplyr)
library(purrr)
library(stringr)
Test_DataFrame <- tibble("Integer_Variable" = c(rep(x = 1:4))," test white space triming " )
)
f_help <- function(x,side = "left") {
str_to_upper(x) %>%
str_trim(side = side) # %>%
# str_squish() # note that this is commented out
}
modify_if(.x = Test_DataFrame,.f = f_help,side = "left")
# A tibble: 4 x 2
# Integer_Variable Character_Variable
# <int> <chr>
# 1 "TESTER TO UPPER"
# 2 "TEST SQUISHING"
# 3 "CANITCOMPREHEND?.,-0(`KLJNDSFIUHAWERAERIOU140987645=ERROR?"
# 4 "TEST WHITE SPACE TRIMING "
# Note the right sided white space is still preent! It worked!!!
解决方法
据我了解，有两种方法可以解决此问题
- 使用辅助功能
- 使用
purrr::compose
library(dplyr)
library(purrr)
library(stringr)
Test_DataFrame <- tibble("Integer_Variable" = c(rep(x = 1:4)),"Character_Variable" = c("tester to upper","test squishing","canitcomprehend?.,-0(`kljndsfiuhaweraeriou140987645=Error?"," test white space triming " ))
f_help <- function(x,side = "left") {
str_to_upper(x) %>%
str_trim(side = side) %>%
str_squish()
}
modify_if(.x = Test_DataFrame,.p = is.character,.f = f_help,side = "left"
)
#> # A tibble: 4 x 2
#> Integer_Variable Character_Variable
#> <int> <chr>
#> 1 1 TESTER TO UPPER
#> 2 2 TEST SQUISHING
#> 3 3 CANITCOMPREHEND?.,-0(`KLJNDSFIUHAWERAERIOU140987645=ERROR?
#> 4 4 TEST WHITE SPACE TRIMING
modify_if(.x = Test_DataFrame,.f = purrr::compose(str_to_upper,~ str_trim(.x,side = "left"),str_squish)
)
#> # A tibble: 4 x 2
#> Integer_Variable Character_Variable
#> <int> <chr>
#> 1 1 TESTER TO UPPER
#> 2 2 TEST SQUISHING
#> 3 3 CANITCOMPREHEND?.,-0(`KLJNDSFIUHAWERAERIOU140987645=ERROR?
#> 4 4 TEST WHITE SPACE TRIMING
.f的{{1}}参数期望（根据其帮助文件）：
modify_if()因此，如果您提供向量或列表，则A function,formula,or vector (not necessarily atomic).
If a function,it is used as is.
If a formula,e.g. ~ .x + 2,it is converted to a function.
There are three ways to refer to the arguments:
For a single argument function,use .
For a two argument function,use .x and .y
For more arguments,use ..1,..2,..3 etc
This syntax allows you to create very compact anonymous functions.
If character vector,numeric vector,or list,it is converted to an extractor function.
Character vectors index by name and numeric vectors index by position; use a list to index
by position and name at different levels. If a component is not present,the value of
.default will be returned.
试图将您的值强制为索引（并且失败）。您有两种选择。首先，您可以创建自己的自定义函数来实现所需的功能：
modify_if或者您可以将该函数编写为匿名函数。
custom_function < function(x) {
str_squish(str_trim(str_to_upper(x),side = "left"))
}
modify_if(.x = Test_DataFrame,.f = custom_function
)
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