将通用功能应用于所有数据帧并返回具有相同名称的数据帧 [英] Apply common function to all data frames and return data frames with same name

问题描述

我正在尝试将函数应用于R中的全局环境中的所有相似拼写的数据帧.我想将此函数应用于所有这些数据帧，但是如果不指定我就无法弄清楚该如何做一一一.我想用以前的拼写方式将数据框返回到全局环境.

I'm trying to apply a function to all similarly spelled data frames in my global environment in R. I want to apply this function to all these data frames, but I can't figure out how to do it without me specifying 1 by 1. I want to return the data frame to the global environment with the same spelling as it was before.

mtcars_test = mtcars
iris_test = iris
#....etc......could be 2 of them or 88 of them...but they will all end in "_test"

# figure out what data frames I am working with
list_of_my_dfs = lapply(ls(pattern = "*_test"), get)

#my function just multiples everything by 2
mytest_function = function(df){ df = df*2; return(df)}

helpme_return_these_dfs_to_outside_the_list=plyr::llply(list_of_my_dfs, mytest_function)

这是我需要帮助的地方.我想将函数应用于列表中的每个数据框，然后将数据框从该列表返回"到我的环境中.因此，mtcars_test和所有其他数据帧将在任何地方都乘以2，然后返回全局环境.

This is where I need help. I want to apply my function to each data frame within the list AND then 'return' the data frame from that list to my environment. So mtcars_test and all other data frames will be multiplied by 2 everywhere and returned back to global environment.

推荐答案

1)环境下标将e设置为包含数据框的环境，然后获取其名称并对其进行遍历，如图所示:

1) environment subscripting Set e to the environment containing the data frames and then get their names and loop over them as shown:

BOD_test <- BOD  # not all columns of iris are numeric so use BOD instead
mtcars_test <- mtcars

e <- .GlobalEnv
nms <- ls(pattern = "_test$", envir = e)
for(nm in nms) e[[nm]] <- mytest_function(e[[nm]])

1a)分配最后一个语句的替代方法是:

1a) assign An alternative to the last statement would be:

for(nm in nms) assign(nm, mytest_function( get(nm, e) ), e)

2)列表，您可能希望将数据框保留在列表中:

2) lists You might want, instead, to keep the data frames in a list:

L <- sapply(nms, get, envir = e, simplify = FALSE)
L[] <- lapply(L, mytest_function)

2a)，或者如果您不想覆盖L，则:

2a) sapply or if you do not want to overwrite L then:

sapply(L, mytest_function, simplify = FALSE)

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