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From 颜发才(Yan Facai) <facai....@gmail.com>
Subject Re: Read file and represent rows as Vectors
Date Thu, 06 Apr 2017 05:36:22 GMT
You can try `mapPartitions` method.

example as below:
http://homepage.cs.latrobe.edu.au/zhe/ZhenHeSparkRDDAPIExamples.html#mapPartitions

On Mon, Apr 3, 2017 at 8:05 PM, Old-School <giorgos_myrianthous@outlook.com>
wrote:

> I have a dataset that contains DocID, WordID and frequency (count) as shown
> below. Note that the first three numbers represent 1. the number of
> documents, 2. the number of words in the vocabulary and 3. the total number
> of words in the collection.
>
> 189
> 1430
> 12300
> 1 2 1
> 1 39 1
> 1 42 3
> 1 77 1
> 1 95 1
> 1 96 1
> 2 105 1
> 2 108 1
> 3 133 3
>
>
> What I want to do is to read the data (ignore the first three lines),
> combine the words per document and finally represent each document as a
> vector that contains the frequency of the wordID.
>
> Based on the above dataset the representation of documents 1, 2 and 3 will
> be (note that vocab_size can be extracted by the second line of the data):
>
> val data = Array(
> Vectors.sparse(vocab_size, Seq((2, 1.0), (39, 1.0), (42, 3.0), (77, 1.0),
> (95, 1.0), (96, 1.0))),
> Vectors.sparse(vocab_size, Seq((105, 1.0), (108, 1.0))),
> Vectors.sparse(vocab_size, Seq((133, 3.0))))
>
>
> The problem is that I am not quite sure how to read the .txt.gz file as RDD
> and create an Array of sparse vectors as described above. Please note that
> I
> actually want to pass the data array in the PCA transformer.
>
>
>
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