title: PySpark: TypeError: 'Column' object is not callable
body: <p>I'm loading data from HDFS, which I want to filter by specific variables. But somehow the Column.isin command does not work. It throws this error:</p>
  
  <blockquote>
    <p>TypeError: 'Column' object is not callable</p>
  </blockquote>
  
  <pre><code>from pyspark.sql.functions import udf, col
  variables = ('852-PI-769', '812-HC-037', '852-PC-571-OUT')
  df = sqlContext.read.option("mergeSchema", "true").parquet("parameters.parquet")
  same_var = col("Variable").isin(variables)
  df2 = df.filter(same_var)
  </code></pre>
  
  <p>The schema looks like this:</p>
  
  <pre><code>df.printSchema()
  root
   |-- Time: timestamp (nullable = true)
   |-- Value: float (nullable = true)
   |-- Variable: string (nullable = true)
  </code></pre>
  
  <p>Any idea what am I doing wrong? PS: It's Spark 1.4 with Jupyter Notebook.</p>