many thanks, Peter. On Wed, Sep 7, 2016 at 10:14 PM, Peter Figliozzi <pete.figlio...@gmail.com> wrote:
> Here's a decent GitHub book: Mastering Apache Spark > <https://www.gitbook.com/book/jaceklaskowski/mastering-apache-spark/details> > . > > I'm new at Scala too. I found it very helpful to study the Scala language > without Spark. The documentation found here > <http://docs.scala-lang.org/index.html> is excellent. > > Pete > > On Wed, Sep 7, 2016 at 1:39 AM, 颜发才(Yan Facai) <yaf...@gmail.com> wrote: > >> Hi Peter, >> I'm familiar with Pandas / Numpy in python, while spark / scala is >> totally new for me. >> Pandas provides a detailed document, like how to slice data, parse file, >> use apply and filter function. >> >> Do spark have some more detailed document? >> >> >> >> On Tue, Sep 6, 2016 at 9:58 PM, Peter Figliozzi <pete.figlio...@gmail.com >> > wrote: >> >>> Hi Yan, I think you'll have to map the features column to a new >>> numerical features column. >>> >>> Here's one way to do the individual transform: >>> >>> scala> val x = "[1, 2, 3, 4, 5]" >>> x: String = [1, 2, 3, 4, 5] >>> >>> scala> val y:Array[Int] = x slice(1, x.length - 1) replace(",", "") >>> split(" ") map(_.toInt) >>> y: Array[Int] = Array(1, 2, 3, 4, 5) >>> >>> If you don't know about the Scala command line, just type "scala" in a >>> terminal window. It's a good place to try things out. >>> >>> You can make a function out of this transformation and apply it to your >>> features column to make a new column. Then add this with >>> Dataset.withColumn. >>> >>> See here >>> <http://stackoverflow.com/questions/35227568/applying-function-to-spark-dataframe-column> >>> on how to apply a function to a Column to make a new column. >>> >>> On Tue, Sep 6, 2016 at 1:56 AM, 颜发才(Yan Facai) <yaf...@gmail.com> wrote: >>> >>>> Hi, >>>> I have a csv file like: >>>> uid mid features label >>>> 123 5231 [0, 1, 3, ...] True >>>> >>>> Both "features" and "label" columns are used for GBTClassifier. >>>> >>>> However, when I read the file: >>>> Dataset<Row> samples = sparkSession.read().csv(file); >>>> The type of samples.select("features") is String. >>>> >>>> My question is: >>>> How to map samples.select("features") to Vector or any appropriate type, >>>> so I can use it to train like: >>>> GBTClassifier gbdt = new GBTClassifier() >>>> .setLabelCol("label") >>>> .setFeaturesCol("features") >>>> .setMaxIter(2) >>>> .setMaxDepth(7); >>>> >>>> Thanks. >>>> >>> >>> >> >
