r - 找不到函数“as.data.frame.ffdf”

Question

我正在使用 R 遵循 Big Data Analytics指南。但as.data.frame.ffdf似乎缺少该功能。

有人有想法吗？或者有没有替代的解决方案？

这是示例代码：

# Data were downloaded from Bureau of Transportation Statistics:
# http://www.transtats.bts.gov/DL_SelectFields.asp?Table_ID=236&DB_Short_Name=On-Time
library(Hmisc);library(ff);library(ffbase)
flights.ff <- read.table.ffdf(file = "flights_sep_oct15.txt",
                              sep = ",", VERBOSE = T,
                              header = T, next.rows = 100000,
                              colClasses = NA)
describe(as.data.frame.ffdf(flights.ff$DISTANCE))