Hello expert

I am new to spark. I am using same price of code but getting different results

When i am using below piece of code, i am getting error

py4j.Py4JException: Method or([class java.lang.String]) does not exist

df.filter(F.col("state").isNull()

     | F.col("state")==""

     | F.col("state").contains("")

     | F.col("number").isNull()).show()

However when i am using below piece of code, its working fine

df.withColumn("state",

       F.when(F.col("state")=="",None)

       .otherwise(F.col("state"))).show()

The same F.col("state")=="" code is working in one place but not working in other