使用 dplyr tidyr 在摘要 table 中保留输入变量和因子水平的顺序

Preserve order of input variables and factor levels in summary table, using dplyr tidyr

我喜欢 dplyrtidyr 如此轻松地创建具有多个预测变量和结果变量的单个摘要 table。让我难过的一件事是 preserving/defining 输出 table 中预测变量的顺序及其因子水平的最后一步。

我想出了一个解决方案(如下),其中涉及使用 mutate 手动创建一个结合了预测变量和预测变量值的因子变量(例如 "gender_female")具有所需输出顺序的级别。但是如果变量比较多,我的方案就有点啰嗦了,请问有没有更好的办法?

library(dplyr)
library(tidyr)
levels_eth <- c("Maori", "Pacific", "Asian", "Other", "European", "Unknown")
levels_gnd <- c("Female", "Male", "Unknown")

set.seed(1234)

dat <- data.frame(
  gender    = factor(sample(levels_gnd, 100, replace = TRUE), levels = levels_gnd),
  ethnicity = factor(sample(levels_eth, 100, replace = TRUE), levels = levels_eth),
  outcome1  = sample(c(TRUE, FALSE), 100, replace = TRUE),
  outcome2  = sample(c(TRUE, FALSE), 100, replace = TRUE)
)

dat %>% 
  gather(key = outcome, value = outcome_value, contains("outcome")) %>%
  gather(key = predictor, value = pred_value, gender, ethnicity) %>%
  # Statement below creates variable for ordering output
  mutate(
    pred_ord = factor(interaction(predictor, addNA(pred_value), sep = "_"),
                      levels = c(paste("gender", levels(addNA(dat$gender)), sep = "_"),
                                 paste("ethnicity", levels(addNA(dat$ethnicity)), sep = "_")))
  ) %>%
  group_by(pred_ord, outcome) %>%
  summarise(n = sum(outcome_value, na.rm = TRUE)) %>%
  ungroup() %>%
  spread(key = outcome, value = n) %>%
  separate(pred_ord, c("Predictor", "Pred_value"))

Source: local data frame [9 x 4]

  Predictor Pred_value outcome1 outcome2
      (chr)      (chr)    (int)    (int)
1    gender     Female       25       27
2    gender       Male       11       10
3    gender    Unknown       12       15
4 ethnicity      Maori       10        9
5 ethnicity    Pacific        7        7
6 ethnicity      Asian        6       12
7 ethnicity      Other       10        9
8 ethnicity   European        5        4
9 ethnicity    Unknown       10       11
Warning message:
attributes are not identical across measure variables; they will be dropped 

上面的 table 是正确的,因为 Predictor 和 Predictor 值都没有按字母顺序排序。

编辑

根据要求,这是使用默认排序(字母顺序)时生成的内容。这是有道理的,因为当这些因素组合在一起时,它们被转换为一个字符变量,所有属性都被删除。

dat %>% 
  gather(key = outcome, value = outcome_value, contains("outcome")) %>%
  gather(key = predictor, value = pred_value, gender, ethnicity) %>%
  group_by(predictor, pred_value, outcome) %>%
  summarise(n = sum(outcome_value, na.rm = TRUE)) %>%
  spread(key = outcome, value = n)

Source: local data frame [9 x 4]

  predictor pred_value outcome1 outcome2
      (chr)      (chr)    (int)    (int)
1 ethnicity      Asian        6       12
2 ethnicity   European        5        4
3 ethnicity      Maori       10        9
4 ethnicity      Other       10        9
5 ethnicity    Pacific        7        7
6 ethnicity    Unknown       10       11
7    gender     Female       25       27
8    gender       Male       11       10
9    gender    Unknown       12       15
Warning message:
attributes are not identical across measure variables; they will be dropped 

你可以在没有特殊包的情况下以更简洁有效的方式完成此操作:

rbind(aggregate(dat[,colnames(dat) %in% c("outcome1", "outcome2")], 
                by = list(dat$gender), sum),
      aggregate(dat[,colnames(dat) %in% c("outcome1", "outcome2")], 
                by = list(dat$ethnicity), sum))

它以简单直接的方式汇总了多个预测变量和结果变量,并且还避免了必须创建属于您提到的复杂解决方案的一部分的变量。

   Group.1 outcome1 outcome2
1   Female       25       27
2     Male       11       10
3  Unknown       12       15
4    Maori       10        9
5  Pacific        7        7
6    Asian        6       12
7    Other       10        9
8 European        5        4
9  Unknown       10       11

如果您想重命名上面的列,只需将其分配给一个对象(例如 mytable <-)并重命名它们(即 colnames(mytable) <- c("Pred_value", "outcome1", "outcome2"))。如果要键入的变量太多,您也可以使用 apply 来扩大它。

如果您希望您的数据是这样排列的因子,您需要将它们转换回因子,因为 gather 强制转换为字符(它会警告您)。您可以使用 gatherfactor_key 参数来处理 predictor,但是 pred_value 需要 assemble 级别,因为它现在结合了两个因素从原来的。简化一点:

library(tidyr)
library(dplyr)

dat %>% 
    gather(key = predictor, value = pred_value, gender, ethnicity, factor_key = TRUE) %>%
    group_by(predictor, pred_value) %>% 
    summarise_all(sum) %>%
    ungroup() %>% 
    mutate(pred_value = factor(pred_value, levels = unique(c(levels_eth, levels_gnd), 
                                                           fromLast = TRUE))) %>% 
    arrange(predictor, pred_value)

## # A tibble: 9 × 4
##   predictor pred_value outcome1 outcome2
##      <fctr>     <fctr>    <int>    <int>
## 1    gender     Female       25       27
## 2    gender       Male       11       10
## 3    gender    Unknown       12       15
## 4 ethnicity      Maori       10        9
## 5 ethnicity    Pacific        7        7
## 6 ethnicity      Asian        6       12
## 7 ethnicity      Other       10        9
## 8 ethnicity   European        5        4
## 9 ethnicity    Unknown       10       11

请注意,您需要使用 uniquefromLast = TRUE 将重复的 "Unknown" 值排列在正确的位置; union会提早一点

您可以在变量前加上强制它们按正确顺序排列的值,例如“X1_gender”、“X2_ethnicity”。前缀可以在末尾用 mutate 去除。这可能不是一个“整洁”的解决方案,但它对我的目的有用,解决了导致我出现此问题的问题 post。

library(dplyr)
library(tidyr)
levels_eth <- c("Maori", "Pacific", "Asian", "Other", "European", "Unknown")
levels_gnd <- c("Female", "Male", "Unknown")

set.seed(1234)

dat <- data.frame(
  X1_gender    = factor(sample(levels_gnd, 100, replace = TRUE), levels = levels_gnd),
  X2_ethnicity = factor(sample(levels_eth, 100, replace = TRUE), levels = levels_eth),
  outcome1  = sample(c(TRUE, FALSE), 100, replace = TRUE),
  outcome2  = sample(c(TRUE, FALSE), 100, replace = TRUE)
)

dat %>% 
  gather(key = outcome, value = outcome_value, contains("outcome")) %>%
  gather(key = predictor, value = pred_value, X1_gender, X2_ethnicity) %>%
  group_by(predictor, pred_value, outcome) %>%
  summarise(n = sum(outcome_value, na.rm = TRUE)) %>%
  spread(key = outcome, value = n) %>%
  mutate(predictor=gsub("^X[0-9]_","", predictor))
 

结果:

`summarise()` regrouping output by 'predictor', 'pred_value' (override with 
`.groups` argument)
# A tibble: 9 x 4
# Groups:   predictor, pred_value [9]
  predictor pred_value outcome1 outcome2
  <chr>     <chr>         <int>    <int>
1 gender    Female           16       21
2 gender    Male             12       15
3 gender    Unknown          18       16
4 ethnicity Asian             4        6
5 ethnicity European         13       13
6 ethnicity Maori             4        6
7 ethnicity Other             7       11
8 ethnicity Pacific          10        9
9 ethnicity Unknown           8        7
Warning message:
attributes are not identical across measure variables;
they will be dropped