如何计算SparkDataframe中的列数？

我在Spark中有这个数据框我想要计算它中可用列的数量.我知道如何计算列中的行数,但我想计算列数.

val df1 = Seq(
    ("spark", "scala",  "2015-10-14", 10,"rahul"),
    ("spark", "scala", "2015-10-15", 11,"abhishek"),
    ("spark", "scala", "2015-10-16", 12,"Jay"),
    ("spark","scala",null,13,"Kiran"))
  .toDF("bu_name","client_name","date","patient_id","paitent _name")
df1.show

任何人都可以告诉我如何计算此数据帧中的列数？我使用的是Scala语言.

要计算列数,只需执行以下操作:

df1.columns.size