在dplyr中使用重命名和列不存在时避免错误 [英] Avoiding error when using rename in dplyr and column doesn't exist

问题描述

在某些情况下，不存在在dplyr中使用重命名功能的聪明方法吗？

Is there a clever way to use the rename function in dplyr when in some instances the column to be renamed doesn't exist?

例如，我想以下内容不会导致错误

For example, I would like the following not to result in an error

mtcars%>%rename(miles_per_gallon=mpg,missing_varible=foo)

（结果：错误：未知变量：foo。）

(results in this: Error: Unknown variables: foo.)

，而是完成了所有可能的重命名的数据框。

but rather the dataframe with all possible renaming done.

当前，我正在重命名之前明确检查特定列是否存在

Currently I am explicitly checking that the specific column exists before renaming

谢谢

伊恩

推荐答案

有时可以不执行 dplyr 中的所有操作。这可能是其中之一。我将设置一个用作键的向量：

Sometimes it's okay to not do everything in dplyr. This may be one of those times. I would set up a vector that operates as a key:

namekey <- c(mpg="miles_per_gallon", cyl="cylinders", disp="displacement", hp="horse_power",
             drat="rear_axle_ratio", wt="weight", qsec="quarter_mile_time", vs="v_s",
             am="transmission", gear="number_of_gears", carb="number_of_carburetors",
             foo="missing_variable")

mtcars1 <- mtcars[,1:2]
mtcars1$foo <- rnorm(nrow(mtcars1))

names(mtcars1) <- namekey[names(mtcars1)]

head(mtcars1)
#                   miles_per_gallon cylinders missing_variable
# Mazda RX4                     21.0         6       -0.9901081
# Mazda RX4 Wag                 21.0         6        0.2338014
# Datsun 710                    22.8         4       -0.3077473
# Hornet 4 Drive                21.4         6        1.1200518
# Hornet Sportabout             18.7         8        0.7482842
# Valiant                       18.1         6        0.4206614

一旦您拥有密钥，它只是一条简单易懂的重命名的代码。

Once you have your key, it's just a single, easy-to-understand line of code that does the rename.

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