Questions tagged [apache-spark]
Apache Spark is an open source cluster computing system that aims to make data analytics fast — both fast to run and fast to write.
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Reading and analyzing CSV using Spark Scala
I am looking to tune the performance in the below code which write the data in partition format.
I am reading the csv data and writing to HDFS. What are the parameters I can consider to enhance the ...
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Graph coloring problem with Spark (JAVA)?
I am trying to create the algorithm described in the image from this link
Simply put any two adjacent nodes must not share tuples and if they do they are colored with the same color. If there's a ...
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PySpark SCD Type 1
I am using PySpark in Azure DataBricks to try to create a SCD Type 1.
I would like to know if this is an efficient way of doing this?
Here is my SQL table:
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Group events close in time into sessions and assign unique session IDs
The following is a trimmed-down example of my actual code, but it suffices to show the algorithmic problem I'm trying to solve.
Given is a DataFrame with events, each with a user ID and a timestamp.
<...
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Rewriting scala code in object-oriented style style to reduce repetitive use of similar functions
I need help in rewriting my code to be less repetitive. I am used to coding procedural and not object-oriented. My scala program is for Databricks.
how would you combine cmd 3 and 5 together? Does ...
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Spark Scala: SQL rlike vs Custom UDF
I've a scenario where 10K+ regular expressions are stored in a table along with various other columns and this needs to be joined against an incoming dataset. Initially I was using "spark sql rlike" ...
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699
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Scala app to transpose columns into rows
This is the first application or really any Scala I have every written. So far it functions as I would hope it would. I just found this community and would love some peer review of possible ...
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Filtering and creating new columns by condensing the lists for each item information
I am trying to improve my programming skills at work (analyst) and one of the engineering projects I worked is around ETL. Essentially, we roll up all individuals account information to a single row ...
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Quantiles calculation in Pyspark MLib
I am trying to find out quantiles for each column on the table for various firms using spark 1.6
I have around 5000 entries in firm_list and 300 entries in attr_lst...
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spark takes long time for checking an array of items present in another array
I am new to spark. I have two dataframes df1 and df2. df1 has three rows. df2 has more than few million rows. I want to check whether all items in df2 are in transaction of df1, if so sum up the costs....
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Binary check code in pyspark
I am trying to find out if a column is binary or not. If a column is only having 1 or 0 then I am flagging it as binary, else ...
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Managing PySpark DataFrames
I was successfully able to write a small script using PySpark to retrieve and organize data from a large .xml file. Being new to using PySpark, I am wondering if there is any better way to write the ...
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Function to generate pyspark diff and return differences in line
I have written a function that takes two pyspark dataframes and creates a diff in line. I am struggling to get it to scale with 100s of columns. I get around the for...
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Large dataset with pyspark - optimizing join, sort, compare between rows and group by with aggregation
I have a csv file with more than 700,000,000 records in this structure:
...
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Joining Apache Spark data frames, with many conditional substitutions
I am joining two data frame in spark using scala .
My code looks very ugly because of the multiple when condition .
Can somebody please help me simplify my code?
Here is my existing code .
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Apache spark compaction script to handle small files in hdfs
I have some use cases where I have small parquet files in Hadoop, say, 10-100 MB. I would to compact them so as to have files at least say 100 MB or 200 MB.
The logic of my code is to:
* find a ...
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Adding columns in Spark dataframe based on rules
I have a dataframe df, which contains below data:
...
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165
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Reduce sample rate of GPS data based on distance between points
The algorithm needs to reduce an RDD[GPSRecord] based on the distance between several points, e.g. "give me only GPS records when the distance between them exceeds ...
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Pyspark Solver for Tiered Board Games
I've written a Pyspark program that will completely solve a tiered board game (no loops, each game position is a member of only one tier) and writes each tier to a file. It also determines the ...
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Classifying and counting database entries using Scala map and flatMap
I am new to Spark and Scala and I have solved the following problem. I have a table in database with following structure:
...
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Unit testing Spark transformation on DataFrame
Looking for suggestions on how to unit test a Spark transformation with ScalaTest. The test class generates a DataFrame from static data and passes it to a transformation, then makes assertion on the ...
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PySpark Dataframes program to process huge amounts of server data from a parquet file
I'm new to spark and dataframes and I'm looking for feedback on what bad or inefficient processes might be in my code so I can improve and learn. My program reads in a parquet file that contains ...
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Python + spark to parse and save logs
I need to parse logs and have got following code. I can see two problems: map().filter() may induce some performance penalties and copy-paste block
parser.py:
<...
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Implementing an inner product using pyspark
I'm trying to implement a dot product using pyspark in order to learn pyspark's syntax.
I've currently implemented the dot product like so:
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Increase performance of Spark-job Collaborative Recommendation.
This is my first Spark Application. I am using "ALS.train" for training the model - Model Factorization. The total time that the Application takes is approx 45 mins.
Note: I think takeOrdered is the ...
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Generic “reduceBy” or “groupBy + aggregate” functionality with Spark DataFrame
Maybe I totally reinvented the wheel, or maybe I've invented something new and useful. Can one of you tell me if there's a better way of doing this? Here's what I'm trying to do:
I want a generic <...
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RandomForest multi-class classification
Below is the code I have for a RandomForest multiclass-classification model. I am reading from a CSV file and doing various transformations as seen in the code. I ...
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3k
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Average movie rankings
Given a list of tuples of the form, (a, b, c), is there a more direct or optimized for calculating the average of all the c's ...
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615
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Class for finding the median of a two-dimensional space
I have a simple static class that it's purpose is given an RDD of Point to find the median of each dimension and return that as a new ...
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Producing a sorted wordcount with Spark
I'm currently learning how to use Apache Spark. In order to do so, I implemented a simple wordcount (not really original, I know). There already exists an example on the documentation providing the ...
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Why does the LR on spark run so slowly?
Because the MLlib does not support the sparse input, I ran the following code, which supports the sparse input format, on spark clusters. The settings are:
5 nodes, each node with 8 cores (all the ...
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