Thanks Gabriel that works. Just curious what's the benefit of using PCollection.by as oppose to PCollection.parallelDo ? In which use case is either better than the other.
On Thu, Feb 20, 2014 at 6:01 AM, Gabriel Reid <[email protected]>wrote: > On Thu, Feb 20, 2014 at 11:59 AM, Jinal Shah <[email protected]> > wrote: > > Somewhat like that as we are also using that same approach but I was more > > thinking of it as > > PTables.asPTable(PCollection<V>, Keyfinder<V>, PType<K>) and return as > > PTable<K,V> > > > > Basically > > KeyFinder<V> is an interface which will have somekind of method like > > findKey(V) returning K from that V or calculated or anyway it wants. > > > > This is pretty much exactly what PCollection#by does. Your proposed > method as you described it would be written as follows using > PCollection#by: > > PCollection<V> collection = ...; > PTable<K, V> table = collection.by(new KeyFinderMapFn(), ptypeForKey); > > > The method is described at > > http://crunch.apache.org/apidocs/0.8.2/org/apache/crunch/PCollection.html#by(org.apache.crunch.MapFn,%20org.apache.crunch.types.PType) > > - Gabriel > > > > > > > > > On Thu, Feb 20, 2014 at 12:07 AM, Gabriel Reid <[email protected] > >wrote: > > > >> > >> > >> > On 20 Feb 2014, at 05:11, Jinal Shah <[email protected]> wrote: > >> > > >> > I didn't knew that, but I was more talking about something like this > >> > PCollection<V> to PTable<K,V> basically. > >> > > >> > >> I think what you want is the PCollection#by method. It takes a MapFn > that > >> maps each value V to a key, and returns a PTable<K,V> > >> > >> - Gabriel > >> > >> > > >> > > >> >> On Wed, Feb 19, 2014 at 5:49 PM, Josh Wills <[email protected]> > >> wrote: > >> >> > >> >> org.apache.crunch.lib.PTables.asPTable is likely what you want. > >> >> > >> >> > >> >> On Wed, Feb 19, 2014 at 3:47 PM, Jinal Shah <[email protected] > > > >> >> wrote: > >> >> > >> >>> Hi everyone, > >> >>> > >> >>> Is there a generic way of converting PCollection to PTable? If not, > Can > >> >> we > >> >>> create a generic class? Because we are having lot of places where we > >> want > >> >>> to perform a join on 2 PCollections so we have to convert it into > >> PTables > >> >>> and then do a join and then convert it into a PCollection. So i was > >> >>> wondering is there a better way of doing this. > >> >>> > >> >>> Thanks > >> >> > >> >> > >> >> > >> >> -- > >> >> Director of Data Science > >> >> Cloudera <http://www.cloudera.com> > >> >> Twitter: @josh_wills <http://twitter.com/josh_wills> > >> >> > >> >
