Question

想象一下，我想在mtcars数据集中记录以下变量：disp，wt和drat。我想将其保存为log_disp，log_wt和log_wt。

我可以记录所有日志并保存：

cols <- c("disp","wt","drat")
mtcars[cols] <- log(mtcars[cols])

然而，这会覆盖我想保留的初始变量。我怎样才能同时转换并保存为新变量？

Answer 1

只需附加作业中的名称：

mtcars[paste("log",cols,sep="_")] <- log(mtcars[cols])

Answer 2

我非常喜欢James＆amp; amp;大卫。还有一个相对简单的dplyr解决方案：

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  "description": "QuickStart package.json from the documentation, supplemented with testing support",

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  "dependencies": {
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    "angular-in-memory-web-api": "~0.3.0",
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  },
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    "typescript": "~2.1.0",

    "canonical-path": "0.0.2",
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    "lodash": "^4.16.4",
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    "karma-jasmine": "^1.0.2",
    "karma-jasmine-html-reporter": "^0.2.2",
    "protractor": "~4.0.14",
    "rimraf": "^2.5.4",

    "@types/node": "^6.0.46",
    "@types/jasmine": "2.5.36"
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}

由于library(dplyr) mutate_at(mtcars, setNames(cols, paste0("log_", cols)), log) # mpg cyl disp hp drat wt qsec vs am gear carb log_disp log_wt log_drat #1 21.0 6 160.0 110 3.90 2.620 16.46 0 1 4 4 5.075174 0.9631743 1.360977 #2 21.0 6 160.0 110 3.90 2.875 17.02 0 1 4 4 5.075174 1.0560527 1.360977 #3 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1 4.682131 0.8415672 1.348073创建了一个命名向量，因此新列将添加到结果中，而不是修改现有列。

Answer 3

我们可以使用tidyverse来提升动态

library(tidyverse)
f1 <- function(data, columns){
 data %>%
      transmute_at(columns, log) %>%
      rename_all(funs(paste("log", columns, sep="_"))) %>%
      bind_cols(data, .)

 }

res <- f1(mtcars, cols)
head(res, 3)
#    mpg cyl disp  hp drat    wt  qsec vs am gear carb log_disp    log_wt log_drat
#1 21.0   6  160 110 3.90 2.620 16.46  0  1    4    4 5.075174 0.9631743 1.360977
#2 21.0   6  160 110 3.90 2.875 17.02  0  1    4    4 5.075174 1.0560527 1.360977
#3 22.8   4  108  93 3.85 2.320 18.61  1  1    4    1 4.682131 0.8415672 1.348073

或使用mutate_at

更改功能

f2 <- function(data, columns){
data %>%
       mutate_at(columns, funs(log = log(.))) %>%
       rename_at(vars(matches('log')), funs(sub('(\\w+)_(\\w+)', "\\2_\\1", .)))
}
f2(mtcars, cols)

注意：dplyr解决方案都使用标准dplyr语法

转换多个变量并使用新名称保存它们

3 个答案: