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You're reading from  Scala for Data Science

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Published inJan 2016
Reading LevelIntermediate
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ISBN-139781785281372
Edition1st Edition
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Pascal Bugnion
Pascal Bugnion
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Pascal Bugnion

Pascal Bugnion is a data engineer at the ASI, a consultancy offering bespoke data science services. Previously, he was the head of data engineering at SCL Elections. He holds a PhD in computational physics from Cambridge University. Besides Scala, Pascal is a keen Python developer. He has contributed to NumPy, matplotlib and IPython. He also maintains scikit-monaco, an open source library for Monte Carlo integration. He currently lives in London, UK.
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Operations on columns


In the previous section, you learned about the different invokers and how they mapped to SQL statements. We brushed over the methods supported by columns themselves, however: we can compare for equality using ===, but what other operations are supported by Slick columns?

Most of the SQL functions are supported. For instance, to get the total donations to candidates whose name starts with "O", we could run the following:

scala> db.withSession { implicit session =>
  Tables.transactions.filter { 
    _.candidate.startsWith("O") 
  }.take(5).list 
}
List[Tables.Transactions#TableElementType] = List(Transaction(Some(1594098)...

Similarly, to count donations that happened between January 1, 2011 and February 1, 2011, we can use the .between method on the date column:

scala> val dateParser = new SimpleDateFormat("dd-MM-yyyy")
dateParser: java.text.SimpleDateFormat = SimpleDateFormat

scala> val startDate = new java.sql.Date(dateParser.parse("01-01-2011").getTime...
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Scala for Data Science
Published in: Jan 2016Publisher: ISBN-13: 9781785281372

Author (1)

author image
Pascal Bugnion

Pascal Bugnion is a data engineer at the ASI, a consultancy offering bespoke data science services. Previously, he was the head of data engineering at SCL Elections. He holds a PhD in computational physics from Cambridge University. Besides Scala, Pascal is a keen Python developer. He has contributed to NumPy, matplotlib and IPython. He also maintains scikit-monaco, an open source library for Monte Carlo integration. He currently lives in London, UK.
Read more about Pascal Bugnion