Data Sciences Challenges

Explore data science challenges on Ewance to build skills employers expect from analysts and ML engineers. Work through challenges on data cleaning, exploratory analysis, modeling, and storytelling with data.

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AnalysisBeginnerNew
Model a City Bike-Share Network as a Graph for Rebalancing
Build a directed weighted graph with stations as nodes and edges as aggregated trip volume over rolling windows. Compute (a) betweenness centrality to find high-traffic stations…
- Graphs
- Networkx
- Shortest Path
Data Structures
DesignBeginnerNew
Redesign an Executive Revenue Dashboard for an E-Commerce Marketplace
Interview the CFO, the head of category, and 2 finance analysts for 30 minutes each to elicit the 6 analytic tasks the dashboard must support (e.g. month-over-month variance, ca…
- Dashboard Design
- Visual Encoding
- Task Analysis
Information and Data Visualization
AnalysisBeginnerNew
Add Indexes to a Slow FinTech Reporting Database
Read the 6 reporting queries and capture their EXPLAIN ANALYZE output on staging (a refresh of prod, around 90M rows). Identify the minimum set of indexes that improves all 6 by…
- Indexing Strategy
- Query Optimization
- Explain Analyze
Introduction to Database Systems
StrategyBeginnerNew
Migrate a Local-Government Records System from MySQL to PostgreSQL
Audit the MySQL schema (around 60 tables) for incompatibilities (case-folding identifiers, ENUM types, TIMESTAMP semantics, character sets). Plan a migration using pgloader for …
- Database Migration
- Postgresql Or Mysql
- Postgresql Or Mysql
Introduction to Database Systems
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Each challenge names the skills it strengthens. Over time, your profile fills with the competences a hiring manager would actually look for.
Why Ewance
AnalysisBeginnerNew
Pick a NoSQL Store for an Event-Stream Sidecar Cache
Set up identical 3-node clusters of Redis 7, KeyDB, and DragonflyDB on equivalent hardware. Run the team's captured 24-hour workload trace (around 180k ops/second, 80/20 read/wr…
- Nosql
- Redis
- Benchmarking
Introduction to Database Systems
CodeBeginnerNew
Bootstrap a Production-Grade CI/CD Pipeline for a Pre-Seed Startup
Audit the current deploy process and document the 6-point checklist of risk it removes. Build the pipeline in GitHub Actions: (1) PR check workflow, (2) main-branch build with m…
- Ci Cd
- Github Actions
- Container Signing
DevOps and Secure Deployment
DesignBeginnerNew
Integrate a Modern Order System with a Legacy SAP ERP
Map the 5 required integrations: order create (sync), pricing inquiry (sync, sub-300ms), inventory availability (sync, with cache), credit check (sync), order status events (asy…
- Enterprise Integration
- SAP Integration
- Apache Camel
Enterprise and Business Software Engineering
CodeBeginnerNew
Model a Trading Order Book with Algebraic Data Types in Haskell
Design ADTs for Side (Buy | Sell), OrderType (Limit | Market | StopLimit), Order, Trade, and BookState. Make illegal states unrepresentable (e.g. a Match can never produce a neg…
- Haskell
- Algebraic Data Types
- Property Based Testing
Functional Programming
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Strategy Analyst
Frame the business question, model the options, build the recommendation. From market sizing to competitive analysis, this role is where strategy consulting meets in-house decision-making.
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CodeBeginnerNew
Convert an Imperative Recommendation Service to Pure Functional Style
Take the Python ranking module (around 900 lines). Identify side-effects (DB reads, cache lookups, logging, time) and lift them to the boundary. Rewrite the ranking core in Scal…
- Scala Programming
- Pure Functions
- Functional Core Imperative Shell
Functional Programming
DesignBeginnerNew
Vendor-Security Review Program for a Series-C SaaS
Design a 3-tier TPRM framework (critical / important / low-risk) with explicit classification criteria (data type, integration depth, downtime impact, regulatory scope). For eac…
- Third Party Risk
- Security Governance
- Compliance
Information Security Management and Governance
CodeBeginnerNew
Build a Search-Based Logistics Router for a Same-Day Delivery Service
Build a Python service exposing /route that takes (courier_location, list_of_stops, traffic_window) and returns an ordered route. Implement 2 search strategies: A* (with a domai…
- Search Algorithms
- Intelligent Agents
- Python Or Javascript
Introduction to Artificial Intelligence (CS Elective)
CodeBeginnerNew
Knowledge-Graph Recommender for a Niche Online Bookstore
Model the catalog as a knowledge graph (nodes: books, authors, genres, themes, eras, awards; edges: wrote, in-genre, has-theme, won, similar-to). Use Neo4j or a simple Python in…
- Knowledge Representation
- Knowledge Graphs
- Python Or Javascript
Introduction to Artificial Intelligence (CS Elective)
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CodeBeginnerNew
Intelligent Agent for a Smart-Thermostat Pricing-Aware Schedule
Design an intelligent agent with: perception (read sensor history), basic learning (cluster comfort intervals from 7 days of observations), decision-making (schedule heating to …
- Intelligent Agents
- Basic Learning
- Python Or Javascript
Introduction to Artificial Intelligence (CS Elective)
CodeBeginnerNew
Churn-Prediction Model for a B2B Vertical SaaS
Use 18 months of anonymized data (provided) covering: usage events, login frequency, support tickets, NPS responses, billing health, feature adoption, practice firmographics. De…
- Supervised Learning
- Python Or Javascript
- Ml Applications
Machine Learning (CS Elective)
AnalysisBeginnerNew
Customer-Segmentation Study for a DTC Subscription Box
Use 18 months of anonymized data: order history, churn events, NPS responses, box-rating data, referral activity, marketing-channel attribution. Engineer features (RFM-style + b…
- Unsupervised Learning
- Python Or Javascript
- Ml Applications
Machine Learning (CS Elective)
CodeBeginnerNew
Build an Embedding-Based Semantic Search for a Legal-Document Corpus
Embed the 380k-document corpus using a multilingual sentence-transformer (e.g. multilingual MPNet or LaBSE). Store embeddings in FAISS or pgvector. Build a search service that r…
- Deep Learning
- Ml Applications
- Python Or Javascript
Machine Learning (CS Elective)
DesignBeginnerNew
Establish IT Governance for a Hyper-Growth Consultancy
Analyze 18 months of SaaS expense data and the failed client-audit report to identify the top 5 governance gaps. Design a framework covering: SaaS procurement (who approves what…
- It Governance
- Saas Management
- Access Management
IT Management and Governance
StrategyBeginnerNew
App Store Launch Strategy for a Bootstrapped SaaS Side-Project
Audit the team's current TestFlight build and Play internal-testing build. Produce: App Store Connect and Play Console store listings with optimized titles, subtitles, keyword r…
- App Distribution
- Store Listing
- Mobile Analytics
Mobile Application Development
CodeBeginnerNew
Native Android Sensor App for Wildlife Conservation Field Surveys
Build a Kotlin + Jetpack Compose Android app targeting API 31+ (covers the field rangers' rugged devices). Implement: GPS-tagged sighting records with species + count + photo, b…
- Mobile Development
- Android Kotlin
- Sensors
Mobile Application Development
CodeBeginnerNew
Refactor a Tangled Java Pricing Engine With Design Patterns
Start from a provided Java 21 codebase with the legacy PricingEngine class, 38 example fixtures (input cart, expected price), and one failing test demonstrating a bug from last …
- Python Or Javascript
- Design Patterns
- Refactoring
Object-Oriented Programming and Design
CodeBeginnerNew
Design a Domain Model for a Library Loan System (Java)
Implement, in Java 21, an Item type hierarchy (Book, AudioBook, Periodical, EquipmentLoan — each with sub-type-specific rules), Member with eligibility logic, Loan as an aggrega…
- Python Or Javascript
- Oo Design
- Domain Modeling
Object-Oriented Programming and Design
CodeBeginnerNew
Apply SOLID to a Java Reporting Service for a Renewable Energy Startup
Receive the legacy ReportService, 4 sample report templates (Daily Output, Monthly P&L, Annual Availability, Curtailment), and 22 fixtures (input dataset, expected report). Refa…
- Python Or Javascript
- Solid Principles
- Refactoring
Object-Oriented Programming and Design
CodeBeginnerNew
Build a Plugin-Based Notification Framework With Observer + Factory
Implement, in Java 21: an EventBus that supports typed subscriptions, a NotificationChannel interface with concrete subtypes (Push, Email, InApp, SMS), an AbstractChannelFactory…
- Python Or Javascript
- Design Patterns
- Oo Design
Object-Oriented Programming and Design
AnalysisBeginnerNew
Cardinality and Cost Control on a Datadog-Based Gaming Platform
Receive an anonymized export of Datadog metric inventory (metric names, tag-cardinality counts, monthly cost per metric, team owner). Identify the top 30 cost-driver metrics, cl…
- Cardinality Control
- Datadog
- Finops & Cost Optimization
Software Observability

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Data Sciences Challenges | Ewance