structType 函数来自 Scala 的 SparkAPI,在 Sparklyr 中,要指定数据类型,您必须将其作为列表传递给“column”参数,假设我们有以下 CSV(data.csv):
name,birthdate,age,height
jader,1994-10-31,22,1.79
maria,1900-03-12,117,1.32
读取相应数据的函数为:
mycsv <- spark_read_csv(sc, "mydate",
path = "data.csv",
memory = TRUE,
infer_schema = FALSE, #attention to this
columns = list(
name = "character",
birthdate = "date", #or character because needs date functions
age = "integer",
height = "double"))
# integer = "INTEGER"
# double = "REAL"
# character = "STRING"
# logical = "INTEGER"
# list = "BLOB"
# date = character = "STRING" # not sure
对于操作日期类型,您必须使用配置单元日期函数,而不是 R 函数。
mycsv %>% mutate(birthyear = year(birthdate))
参考:https ://spark.rstudio.com/articles/guides-dplyr.html#hive-functions