在RStudio中Knitting PDF时遭遇无效参数类型错误

核心错误原因 #

代码里fct_reorder的第二个参数引用了还没创建完成的bll_summarized对象，导致参数类型无效。在管道操作（%>%）的mutate步骤中，当前处理的数据是前一步summarize的结果，直接用列名就行，不用通过未赋值的对象引用。

修正后的代码 #

library(forcats)
library(knitr)
library(dplyr)
library(magrittr)
library(purrr)

bll_summarized <- bll_nyc %>% 
  mutate(borough_id = factor(borough_id, levels = c("1", "2", "3","4","5"), labels = c("Bronx", "Brooklyn", "Manhattan", "Queens", "Staten Island"))) %>%
  group_by(borough_id) %>% 
  summarize(counts_of_bll_greater_than_5 = sum(bll_5)) %>% 
  mutate(borough_id = fct_reorder(borough_id, counts_of_bll_greater_than_5, .desc = FALSE))
bll_summarized

额外排查点 #

• 确认bll_nyc里的bll_5列是数值型或逻辑型（逻辑值求和会自动转成1/0计数），如果是字符型要先转换：mutate(bll_5 = as.numeric(bll_5))
• 检查borough_id原始数据是否为字符型（代码指定的levels是字符串"1"-"5"），如果是数值型要先转换：mutate(borough_id = as.character(borough_id))

内容的提问来源于stack exchange，提问作者Arjun Sridhar Mehta