Learning-Spark | 学习Spark的代码,关于Spark Core、Spark SQL、Spark Streaming、Spark
kandi X-RAY | Learning-Spark Summary
kandi X-RAY | Learning-Spark Summary
学习Spark的代码,关于Spark Core、Spark SQL、Spark Streaming、Spark MLLib
Support
Quality
Security
License
Reuse
Top functions reviewed by kandi - BETA
Currently covering the most popular Java, JavaScript and Python libraries. See a Sample of Learning-Spark
Learning-Spark Key Features
Learning-Spark Examples and Code Snippets
Community Discussions
Trending Discussions on Learning-Spark
QUESTION
I am using structured streaming with schema specified with the help of case class and encoders to get the streaming dataframe.
...ANSWER
Answered 2019-Nov-24 at 05:48It's just working fine for me.
QUESTION
I'm trying to read a stream from a Kafka source containing JSON records using a pattern from the book Learning Spark:
...ANSWER
Answered 2019-Jun-05 at 18:12The method mapPartitions only takes a function:
QUESTION
I have a docker container running on my laptop with a master and three workers, I can launch the typical wordcount example by entering the ip of the master using a command like this:
...ANSWER
Answered 2019-Mar-19 at 17:31This is the command that solves my problem:
QUESTION
I have an RDD in pyspark of the form (key, other things), where "other things" is a list of fields. I would like to get another RDD that uses a second key from the list of fields. For example, if my initial RDD is:
(User1, 1990 4 2 green...)
(User1, 1990 2 2 green...)
(User2, 1994 3 8 blue...)
(User1, 1987 3 4 blue...)
I would like to get (User1, [(1990, x), (1987, y)]),(User2, (1994 z))
where x, y, z would be an aggregation on the other fields, eg x is the count of how may rows I have with User1 and 1990 (two in this case), and I get a list with one tuple per year.
I am looking at the key value functions from: https://www.oreilly.com/library/view/learning-spark/9781449359034/ch04.html
But don't seem to find anything that will give and aggregation twice: once for user and one for year. My initial attempt was with combineByKey() but I get stuck in getting a list from the values.
Any help would be appreciated!
...ANSWER
Answered 2019-Jan-01 at 11:45You can do the following using groupby
:
QUESTION
Can anyone explain me this?
The flipside, however, is that for transformations that cannot be guaranteed to pro‐ duce a known partitioning, the output RDD will not have a partitioner set. For example, if you call map() on a hash-partitioned RDD of key/value pairs, the function passed to map() can in theory change the key of each element, so the result will not have a partitioner. Spark does not analyze your functions to check whether they retain the key. Instead, it provides two other operations, mapValues() and flatMap Values(), which guarantee that each tuple’s key remains the same.
Source Learning Spark by Matei Zaharia, Patrick Wendell, Andy Konwinski, Holden Karau.
...ANSWER
Answered 2018-Apr-27 at 09:46It is pretty simple:
- Partitioner is a function from a key to partition - How does HashPartitioner work?
- Partitioner can be applied on
RDD[(K, V)]
whereK
is the key. - Once you repartitioned using specific
Partitioner
all pairs with same key are guaranteed to reside on the same partition.
Now, let's consider two examples:
map
takes function(K, V) => U
and returnsRDD[U]
- in other words it transforms a wholeTuple2
. It might or might not preserve key as is, it might not even returnRDD[(_, _)]
so partitioning is not preserved.mapValues
takes function(V) => U
and returnsRDD[(K, U)]
- in other words it transforms only values. Key, which determines partition membership, is never touched, so partitioning is preserved.
QUESTION
I try to get a basic regression run with Zeppelin 0.7.2 and Spark 2.1.1 on Debian 9. Both zeppelin are "installed" in /usr/local/ that means /usr/local/zeppelin/ and /usr/local/spark. Zeppelin also knows the correct SPARK_HOME. First I load the data:
...ANSWER
Answered 2017-Aug-18 at 06:39It was a configuration error in Zeppelins conf/zeppelin-env.sh
. There, I had the following line uncommented that caused the error and I now commented the line and it works:
QUESTION
I'm learning Spark by working through some of the examples in Learning Spark: Lightning Fast Data Analysis and then adding my own developments in.
I created this class to get a look at basic transformations and actions.
...ANSWER
Answered 2017-Jul-02 at 11:13This is a feature. With saveAsTextFile
Spark writes a single output file per partition, no matter if it contains data or not. Since you apply filter
some input partitions, which originally contained data, can end up empty. Hence the empty files.
QUESTION
I'm new to Spark so am trying to setup a project from the book Learning Spark: Lightning-Fast Big Data Analysis. The book uses version 1.3 but I've only got 2.1.1 so am trying to work around a few differences.
All the Spark related jars that I'm importing into my Java project have a "import org.apache cannot be resolved". I know it's because the project cannot find the jar files specified.
I can manually add each by going to Build Path > Configure Build path and adding them to the Libraries section but I think I shouldn't need to do this. The project uses Maven so I believe if I have the Spark dependencies configured correctly in my pom.xml it should work. Is this correct?
I also set the following environment variables:
...ANSWER
Answered 2017-Jul-01 at 11:21This should be setup as a Maven project, not a Java project. In my case to resolve deleted the project from my workspace, re-created it in the workspace as a general project, then converted it to a Maven project. I probably should have just set it up as a Maven project at the start.
Community Discussions, Code Snippets contain sources that include Stack Exchange Network
Vulnerabilities
No vulnerabilities reported
Install Learning-Spark
Support
Reuse Trending Solutions
Find, review, and download reusable Libraries, Code Snippets, Cloud APIs from over 650 million Knowledge Items
Find more librariesStay Updated
Subscribe to our newsletter for trending solutions and developer bootcamps
Share this Page