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POConsolidating a data table in Scala
 

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  1. POConsolidating a data table in Scala
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    <p>I am working on a small data analysis tool, and practicing/learning Scala in the process. However I got stuck at a small problem. </p> <p>Assume data of type: </p> <pre><code>X Gr1 x_11 ... x_1n X Gr2 x_21 ... x_2n .. X GrK x_k1 ... x_kn Y Gr1 y_11 ... y_1n Y Gr3 y_31 ... y_3n .. Y Gr(K-1) ... </code></pre> <p>Here I have entries (X,Y...) that may or may not exist in up to K groups, with a series of values for each group. What I want to do is pretty simple (in theory), I would like to consolidate the rows that belong to the same "entity" in different groups. so instead of multiple lines that start with <code>X</code>, I want to have one row with all values from <code>x_11</code> to <code>x_kn</code> in columns. </p> <p>What makes things complicated however is that not all entities exist in all groups. So wherever there's "missing data" I would like to pad with for instance zeroes, or some string that denotes a missing value. So if I have (X,Y,Z) in up to 3 groups, the type I table I want to have is as follows:</p> <pre><code>X x_11 x_12 x_21 x_22 x_31 x_32 Y y_11 y_12 N/A N/A y_31 y_32 Z N/A N/A z_21 z_22 N/A N/A </code></pre> <p>I have been stuck trying to figure this out, is there a smart way to use List functions to solve this? </p> <hr> <p>I wrote this simple loop:</p> <pre><code>for { (id, hitlist) &lt;- hits.groupBy(_.acc) h &lt;- hitlist } println(id + "\t" + h.sampleId + "\t" + h.ratios.mkString("\t")) </code></pre> <p>to able to generate the tables that look like the example above. Note that, my original data is of a different format and layout,but that has little to do with the problem at hand, thus I have skipped all steps regarding parsing. I should be able to use <code>groupBy</code> in a better way that actually solves this for me, but I can't seem to get there. </p> <p>Then I modified my loop mapping the <code>hits</code> to <code>ratios</code> and appending them to one another:</p> <pre><code>for ((id, hitlist) &lt;- hits.groupBy(_.acc)){ val l = hitlist.map(_.ratios).foldRight(List[Double]()){ (l1: List[Double], l2: List[Double]) =&gt; l1 ::: l2 } println(id + "\t" + l.mkString("\t")) //println(id + "\t" + h.sampleId + "\t" + h.ratios.mkString("\t")) } </code></pre> <p>That gets me one step closer but still no cigar! Instead of a fully padded "matrix" I get a jagged table. Taking the example above:</p> <pre><code>X x_11 x_12 x_21 x_22 x_31 x_32 Y y_11 y_12 y_31 y_32 Z z_21 z_22 </code></pre> <p>Any ideas as to how I can pad the table so that values from respective groups are aligned with one another? I should be able to use <code>_.sampleId</code>, which holds the "group membersip" for each "hit", but I am not sure how exactly. ´hits´ is a List of type <code>Hit</code> which is practically a wrapper for each row, giving convenience methods for getting individual values, so essentially a tuple which have "named indices" (such as <code>.acc</code>, <code>.sampleId</code>..) </p> <p>(I would like to solve this problem without hardcoding the number of groups, as it might change from case to case)</p> <p>Thanks!</p>
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    1. COI'm having trouble understanding what you require. Could you post example outputs for the table you posted (the one you want and the one you have?)
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    2. CO@gzm0 added more info, specifically those example outputs you asked for
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