mutate_impl（.data，dots）出错：未找到绑定：

Question

有人可以帮我解决这个问题吗？

文件链接：

orders <- fread("https://s3.amazonaws.com/hackerday.datascience/87/orders.csv")
orders <- orders %>% mutate(order_hour_of_day=as.numeric(order_hour_of_day), 
    eval_set=as.factor(eval_set))

订单$ day_week_name＆lt; -   ifelse（订单$ order_dow == 0，          ＆＃39;周日＆＃39 ;,          ifelse（订单$ order_dow == 1，                 ＆＃39;星期一＆＃39 ;,                 ifelse（订单$ order_dow == 2，                        ＆＃39;星期二＆＃39 ;,                        ifelse（订单$ order_dow == 3，                               ＆＃39;星期三＆＃39 ;,                               ifelse（订单$ order_dow == 4，                                      ＆＃39;周四＆＃39 ;,                                      ifelse（订单$ order_dow == 5，                                             ＆＃39;周五＆＃39 ;,                                             ifelse（订单$ order_dow == 6，                                                    ＆＃39;星期六＆＃39;＆＃34;＆＃34;））））））） 订单$ day_ordered＆lt; - factor（订单$ day_week_name，levels = c（＆＃34; Sunday＆＃34;，                                                              ＆＃34;星期一＆＃34 ;,                                                              ＆＃34;星期二＆＃34 ;,                                                              ＆＃34;星期三＆＃34 ;,                                                              ＆＃34;周四＆＃34 ;,                                                              ＆＃34;周五＆＃34 ;,                                                              ＆＃34;星期六＆＃34））

问题是，当我运行此代码时，我收到以下错误消息，没有情节：

orders %>% filter(eval_set=='prior') %>% count_(orders,'order_number') %>%
ggplot(aes(order_number,n)) + geom_line(color='red',size=1) 

Error Message: 

mutate_impl（.data，dots）中的错误：未找到绑定：先前。 mutate_impl（.data，dots）出错：未找到绑定：星期二。