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Questions tagged [collect]

Use this tag for questions related to the act of gathering/collecting/grouping data/results from several nodes/places/computers to one (or main) resource(s).

Use this tag for questions related to the act of gathering/collecting/grouping data/results from several nodes/places/computers to one (or main) resource(s).

For example, in Distributed Computing, the slaves would do their local computation and eventually, one would like the master to collect the (local) results.

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Difference between map and collect in Ruby?

I have Googled this and got patchy / contradictory opinions - is there actually any difference between doing a map and doing a collect on an array in Ruby/Rails? The docs don't seem to suggest any, but are there perhaps differences in method or…
sscirrus
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Extract a dplyr tbl column as a vector

Is there a more succinct way to get one column of a dplyr tbl as a vector, from a tbl with database back-end (i.e. the data frame/table can't be subset directly)? require(dplyr) db <- src_sqlite(tempfile(), create = TRUE) iris2 <- copy_to(db,…
nacnudus
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what's different between each and collect method in Ruby

From this code I don't know the difference between the two methods, collect and each. a = ["L","Z","J"].collect{|x| puts x.succ} #=> M AA K print a.class #=> Array b = ["L","Z","J"].each{|x| puts x.succ} #=> M AA K print b.class #=> Array
mko
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Collect values from an array of hashes

I have a data structure in the following format: data_hash = [ { price: 1, count: 3 }, { price: 2, count: 3 }, { price: 3, count: 3 } ] Is there an efficient way to get the values of :price as an array like [1,2,3]?
Kert
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pyspark collect_set or collect_list with groupby

How can I use collect_set or collect_list on a dataframe after groupby. for example: df.groupby('key').collect_set('values'). I get an error: AttributeError: 'GroupedData' object has no attribute 'collect_set'
Hanan Shteingart
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Static context cannot access non-static in Collectors

I have group of students. First I want to group them by the marks. Then I want to further group those sets into same name students together. Map>> groupping = students.stream() …
Jude Niroshan
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Scala Partition/Collect Usage

Is it possible to use one call to collect to make 2 new lists? If not, how can I do this using partition?
Adrian Modliszewski
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Java 8 is not maintaining the order while grouping

I m using Java 8 for grouping by data. But results obtained are not in order formed. Map> groupedResult = null; if (!CollectionUtils.isEmpty(groupByColumns)) { Map mapArr[] = new…
Shreya Shah
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ruby using the "&:methodname" shortcut from array.map(&:methodname) for hash key strings rather than methodname

Most ruby developers know how to save a few keystrokes by doing something like this: array.map(&:methodname) rather than array.map {|x| x.methodname } Is there any way I could apply a similar &:methodname shortcut for calling "methods" (values…
boulder_ruby
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Linq Map! or Collect!

What is the Linq equivalent to the map! or collect! method in Ruby? a = [ "a", "b", "c", "d" ] a.collect! {|x| x + "!" } a #=> [ "a!", "b!", "c!", "d!" ] I could do this by iterating over the collection with a foreach, but I…
Jason Marcell
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How to use collect call in Java 8?

Lets say we have this boring piece of code that we all had to use: ArrayList ids = new ArrayList(); for (MyObj obj : myList){ ids.add(obj.getId()); } After switching to Java 8, my IDE is telling me that I can replace this code with…
Alexandru Severin
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Collect only if result is not null

I have a collection and I'm wanting to find certain elements and transform them. I can do this in two closures but I was wondering if it is possible with only one? def c = [1, 2, 3, 4] def result = c.findAll { it % 2 == 0 } result =…
Lerp
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Map an array modifying only elements matching a certain condition

In Ruby, what is the most expressive way to map an array in such a way that certain elements are modified and the others left untouched? This is a straight-forward way to do it: old_a = ["a", "b", "c"] # ["a", "b", "c"] new_a…
Yang Meyer
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Spark: Difference between collect(), take() and show() outputs after conversion toDF

I am using Spark 1.5. I have a column of 30 ids which I am loading as integers from a database: val numsRDD = sqlContext .table(constants.SOURCE_DB + "." + IDS) .select("id") .distinct .map(row=>row.getInt(0)) This is the…
Christos Hadjinikolis
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How to collect DoubleStream to List

I have the following code: Stream.of("1,2,3,4".split(",")).mapToDouble(Double::valueOf).collect(Collectors.toList()); I want to return List. This code doesn't compile. I see error: Error:(57, 69) java: method collect in interface…
gstackoverflow
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