title: How to create spark dataframe with column name which contains dot/period?
body: <p>I have data in a list and want to convert it to a spark dataframe with one of the column names containing a "."</p>
  
  <p>I wrote the below code which ran without any errors.</p>
  
  <pre><code>input_data = [('retail', '2017-01-03T13:21:00', 134),
                       ('retail', '2017-01-03T13:21:00', 100)]
  rdd_schema = StructType([StructField('business', StringType(), True), \
                           StructField('date', StringType(), True), \
                           StructField("`US.sales`", FloatType(), True)])
  input_mock_df = spark.createDataFrame(input_mock_rdd_map, rdd_schema)
  </code></pre>
  
  <p>The below code returns the column names</p>
  
  <pre><code>input_mock_df.columns
  </code></pre>
  
  <p>But any operations on this dataframe is giving error for example</p>
  
  <pre><code>input_mock_df.count()
  </code></pre>
  
  <p>How do I make a valid spark dataframe which contains a "."?</p>
  
  <p><strong>Note</strong>: </p>
  
  <ul>
  <li>I dont give "." in the column name the code works perfectly.</li>
  <li>I want to solve it using native spark and not use pandas etc</li>
  </ul>