英文:
Specify levels when `mutate`-ing dataframe variables to factors
问题
让我们假设我有名为 data 的以下 tibble 数据框：
library(tibble)data <- tribble(~"ID", ~"some factor", ~"some other factor",1L, "low", "high",2L, "very high", "low",3L, "very low", "low",4L, "high", "very high",5L, "very low", "very low")
我使用 forcats 中的 fct() 函数来相应地转换我的两个因子变量：
library(dplyr)library(forcats)data <- data %>%mutate(across(starts_with("some"), fct))
这会给我以下结果：
# A tibble: 5 × 3ID `some factor` `some other factor`<int> <fct> <fct>1 1 low high2 2 very high low3 3 very low low4 4 high very high5 5 very low very low
然而，当我以这种方式调用 fct 时，我不清楚如何指定这个有序变量的级别。我想要的顺序是：
order <- c("very low", "low", "high", "very high")
我该如何使用 dplyr 的函数集来实现这一点？ 目标是创建 ggplot2 可视化图表以遵循这个顺序。
英文:
Let's say I have the following tibble dataframe called data:
library(tibble)data <- tribble(~"ID", ~"some factor", ~"some other factor",1L, "low", "high",2L, "very high", "low",3L, "very low", "low",4L, "high", "very high",5L, "very low", "very low")
I use the fct() function in forcats to convert my two factor variables accordingly:
library(dplyr)library(forcats)data <- data %>%mutate(across(starts_with("some"), fct))
Which gives me:
# A tibble: 5 × 3ID `some factor` `some other factor`<int> <fct> <fct>1 1 low high2 2 very high low3 3 very low low4 4 high very high5 5 very low very low
However, when I call fct this way it's unclear to me how to specify the levels of this ordinal variable. The order I would like is:
order <- c("very low", "low", "high", "very high")
How should I do this with dplyr's set of functions? The goal is to have ggplot2 visualizations that respect this ordering.
答案1
得分: 3
order <- c("very low", "low", "high", "very high")
data <- data %>%
mutate(across(starts_with("some"), fct, order))
应该可以解决问题。
英文:
order <- c("very low", "low", "high", "very high")data <- data %>%mutate(across(starts_with("some"), fct, order))
should do the trick
答案2
得分: 3
当您使用across()时，可以通过across的...参数将额外的参数传递给调用的函数。
data <- data %>%mutate(across(starts_with("some"), fct, levels = order))
这等同于
data <- data %>%mutate(across(starts_with("some"), function(x) fct(x, levels = order)))
（这是R中的一种常见范例，许多函数在应用函数时都有一个...参数，用于传递给应用的函数，还可以参考lapply、sapply、purrr::map等函数。）
英文:
When you use across() you can pass extra arguments along to the called function through across's ....
data <- data %>%mutate(across(starts_with("some"), fct, levels = order))
This is equivalent to
data <- data %>%mutate(across(starts_with("some"), function(x) fct(x, levels = order)))
(This is a common paradigm in R, many functions where you are applying a function have a ... argument for arguments that will be passed along to the applied function, see also lapply, sapply, purrr::map, etc.)
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