Questions tagged [data-engineering]

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9 views

How to perform feature selection on a dataset using correlation-based feature selection process

I have a dataset and on that, I have to perform feature selection using a correlation-based feature selection process (using scikit-learn), can anyone please show me how to do it with a small example ...
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2answers
23 views

When Does Feature Selection Takes Place?

I have a dataset where there are categorical features as well as numeric features, and I have to perform OneHotEncoding, Normalization and feature selection on it. In what order should I perform these ...
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14 views

Spark Dataframe APIs vs Spark SQL

I have a relatively complex query which runs against a database and contains multiple join statements, lead/lag functions, subquery, etc. These tables are available as individual files in my object ...
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0answers
12 views

Best Technologies opening Large Sets of Sensor Time-Series Data to Analytics

My team is exploring options to create a robust "analytics" capability that is well-suited for our large quantities of sensor test data. I'd appreciate any suggestions for technologies that ...
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1answer
33 views

Alternative to EC2 for running ML batch training jobs on AWS

We are building an ML pipeline on AWS, which will obviously require some heavy-compute components including preprocessing and batch training. Most the the pipeline is on Lambda, but Lambda is known to ...
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2answers
170 views

How do I replace NaN values using group by pivot_table in pandas DataFrame?

I am working on a machine learning practice problem, from https://datahack.analyticsvidhya.com/contest/practice-problem-big-mart-sales-iii/#ProblemStatement I want to replace the null values in the ...
3
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1answer
45 views

Storing Large dataset for processing and analysis of data

I am new to data engineering and wanted to know , what is the best way to store more than 3000 GB of data for further processing and analysis ? I am specifically looking for open source resources . I ...
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1answer
34 views

Transitioning from a python script for data transformation to BigQuery

So I have a dataset spread over multiple and ever-growing excel files all of which looks like: email order_ID order_date user1@email.com 1234 23-Mar-2021 user2@email.com 1235 23-Mar-2021 user2@...
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0answers
18 views

How to schedule importing data files from SFTP server located on compute engine instance into BigQuery?

What I want to achieve: Transfer hourly coming data files onto a SFTP file server located on a compute engine VM from several different feeds into Bigquery with real-time updates effectively & ...
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1answer
35 views

How to Include Features that Apply to Specific Classes

I'm predicting hours that will be worked for building tasks. Due to the overall low sample size, I've stacked multiple related tasks together into a single model. (There may be 100 total samples in a ...
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2answers
5k views

How to deal with nan values after merging / joining two dataframes? [closed]

A lot of time after merging two pandas dataframes, I end up with NaNs in the new dataframe, that's just how the way it is, because one csv does not have all the ID's that the other has (Two dataframes ...
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3answers
119 views

Advice on where to continue in the field of data engineering and machine learning

I finished a 28 hours Machine learning with python (Basic course) on Udemy, and it was very beneficial. My aim, is to be able to understand what is ML and how to use its concepts while working with ...
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2answers
170 views

ETL and Data Engineering - is it purely the knowledge of tools or is there theory behind it?

I would like to better understand what a good Data Englineer must know or what he does. Job descriptions mostly list tools that are required, such as Python. If it is possible to separate Data ...
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1answer
49 views

The OLAP (On-Line Analytical Processing) cube with 4 dimensions [closed]

A typical OLAP cube looks like this: As I can see, this cube can work with 2 or 3 dimensions, but what if I have 4 dimensions to produce facts? Should I use star schema instead when having more than ...
4
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2answers
85 views

Data Engineering Stack - collect, transform and visualize geospatial data

I'm making a side project, where I collect geospatial data by web scrapping and from OSM API. I've started with simple Java application, however, I would like to make it as a data flow, purely for ...
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0answers
15 views

Efficient way of adding new columns to datamart without reprocessing complete pipeline

I have a software engineering background and relatively new to data engineering. I am building out tables/datamarts in our datalake for data scientists and analysts to use. We use Airflow for ...
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1answer
21 views

Creating more than one worker nodes for local windows machine [closed]

I am using windows laptop. And I installed apache spark for my laptop. And I try to measure spark performance by changing spark components. because of that I want to create more than one worker nodes ...
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1answer
53 views

How to run Spark python code in Jupyter Notebook via command prompt

I am trying to import a data frame into spark using Python's pyspark module. For this, I used Jupyter Notebook and executed the code shown in the screenshot below After that I want to run this in CMD ...
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1answer
122 views

Can we add other features along with Text in sentiment analysis

Can we add other features along with Text to a ML model . Like giving text and other features as one input combining them and predict the output value. As model can learn some more better if given ...
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3answers
1k views

Is there a cost associated with converting Koalas dataframe to Spark dataframe?

I know that pandas works "under the hood" with numpy arrays stored in dictionaries. In contrast, Koalas works with the underlying Spark framework. Does that mean that there is no extra cost associated ...
2
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2answers
34 views

Loading models from external source

I have a 500MB model which I am commiting to Git. That is a really bad practice since for newer model versions the repository will be huge. As well, It will slow down all builds for deployments. I ...
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2answers
2k views

how to sort a multi-level pandas data-frame by a particular column?

I want to sort a multi-index pandas dataframe by a column but don't want the entire dataframe to be sorted at once. But rather want to sort by one of the indices. Here is an example of what I mean: ...