Lewin Appleton-Fox, Developer in Wellington, New Zealand
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Lewin Appleton-Fox

Verified Expert  in Engineering

Data Engineer and AWS Developer

Wellington, New Zealand
Toptal Member Since
June 8, 2022

Lewin is a senior data engineer with management experience specializing in AWS, Python, and R and a good mix of technical and soft skills. He has built, trained, and managed teams from the ground up, reconfigured an RStudio Server installation, and developed a model for agricultural greenhouse gas emissions for use by the New Zealand government for IPCCC disclosures. Lewin is competent in writing documentation to ensure project viability and maintains open source software projects.


Python, Snowflake, Data Build Tool (dbt), Databricks, Azure DevOps, Azure Blobs...
New Zealand Post
Python, Snowflake, Data Build Tool (dbt), SQL, Linux, Terraform...
Ministry of Justice
R, RStudio, RStudio Shiny, Linux, SQL, Data Analysis...




Preferred Environment

Visual Studio Code (VS Code), Python, R, Data Build Tool (dbt), Snowflake, Amazon Web Services (AWS), Linux, Hadoop

The most amazing...

...machine learning project I've built was a lead targeting model that improved conversion by 25% over manual targeting.

Work Experience

Data Tech Specialist

2022 - PRESENT
  • Created ETL pipelines for ingesting Parquet and JSON data from Azure Blob Storage into Snowflake.
  • Built internal GUI and CLI tools to streamline a data engineering workflow.
  • Documented and provided training on internal tools.
Technologies: Python, Snowflake, Data Build Tool (dbt), Databricks, Azure DevOps, Azure Blobs, Data Pipelines, Azure, ETL, Business Intelligence (BI), DB, Data, GitHub

Senior Data Engineer

2021 - PRESENT
New Zealand Post
  • Acted as a tech lead for Python and AWS Lambda development.
  • Built CI/CD pipelines using Terraform and GitHub Actions.
  • Trained and mentored junior team members, reviewing code and advising on approach.
Technologies: Python, Snowflake, Data Build Tool (dbt), SQL, Linux, Terraform, Data Engineering, Apache Kafka, R, Git, GitHub, DevOps, Data Analysis, Amazon S3 (AWS S3), AWS Lambda, Data Pipelines, ETL, Data Lakes, Serverless, Business Intelligence (BI), DB, Data, Amazon Web Services (AWS)

Senior Analyst

2020 - 2021
Ministry of Justice
  • Reconfigured and administered an RStudio Server installation for the ministry.
  • Provided training and mentoring to junior analysts on R and RStudio.
  • Produced reports and dashboards for government use.
Technologies: R, RStudio, RStudio Shiny, Linux, SQL, Data Analysis, Business Intelligence (BI), DB, Data

Data Modeler

2020 - 2020
Ministry for Primary Industries
  • Developed a model for agricultural greenhouse gas emissions for use by the New Zealand government for IPCCC disclosures and to inform public policy.
  • Wrote extensive documentation to ensure project viability after the end of my contract.
  • Provided training to permanent team members on how to use and change the model.
  • Designed custom data structures to efficiently store intra-process data.
  • Delivered the project on time and to the agreed specification.
Technologies: R, RStudio, Git, Azure DevOps, Data, GitHub

Junior Machine Learning and Data Engineer

2017 - 2019
Hargreaves Lansdown
  • Developed machine learning models for resource forecasting, customer segmentation, and propensity modeling.
  • Wrote ELT pipelines to ingest data from legacy systems to a Hadoop cluster.
  • Trained and mentored junior team members in R and Python.
  • Built reports and dashboards in Shiny and SSRS (SQL Server Reporting Services).
Technologies: R, Hadoop, Sqoop, Apache Hive, Spark, Linux, RStudio Shiny, SQL, Data Analysis, Data Analytics, Data Visualization, Tableau, Microsoft Power BI, Databases, Pandas, NumPy, Data Pipelines, ETL, Data Lakes, Business Intelligence (BI), DB, Microsoft SQL Server, Data, GitHub, MySQL

Operations MI and Reporting Manager

2015 - 2018
Hargreaves Lansdown
  • Built the operations data team from the ground up. Recruited, trained, and managed the team.
  • Worked with management from the C-suite level down to determine the reporting needs for the operations department. Developed a suite of reports to meet requirements as far as was technically feasible.
  • Developed new reports to make operational processes and risk management easier and more efficient.
  • Performed ad hoc analysis work on request and supervised junior team members to do the same.
  • Managed team members, including carrying out performance reviews, training, setting personal development plans, and providing career advice and support.
Technologies: SQL, R, Data Analysis, Data Visualization, Data Analytics, Team Management, Stakeholder Engagement, Business Intelligence (BI), DB, Microsoft SQL Server, Data, MySQL


`levitate` is based on the Python `thefuzz` (formerly fuzzywuzzy) package for fuzzy string matching. An R port of this already exists, but unlike `fuzzywuzzyR`, levitate is written entirely in R with no external dependencies on `reticulate` or Python. It also offers a couple of extra bells and whistles in the form of vectorized functions.


`icecream` is designed to make print debugging easier. It allows you to print out an expression, its value, and (optionally) which function and file the call originated in.

This is an R port of github.com/gruns/icecream.


`foodwebr` makes it easy to visualize the dependency graph of a set of functions (i.e., who calls who). This can be useful for exploring an unfamiliar codebase or reminding yourself of what you wrote ten minutes ago!


The goal of `lambdar` is to make it easy to run R on AWS Lambda. AWS doesn’t provide support for R out of the box but allows you to provide a custom runtime in a container image or Lambda layers. Lambdar provides:

• An R runtime (thanks to github.com/mdneuzerling/r-on-lambda).
• Tools to build, test and deploy Docker containers containing your code.

The process is simple. You write your code as usual, decorate your Lambda function with a roxygen-style `@lambda` tag, and `lambdar` does the rest. It’s designed to drop on top of your existing work with almost no changes to your code.


R, SQL, Python, Snowflake


Pandas, NumPy


Business Intelligence (BI), ETL, DevOps, Azure DevOps


DB, Microsoft SQL Server, Databases, Amazon S3 (AWS S3), Data Lakes, Data Pipelines, MySQL, Apache Hive, Azure Blobs


Data Engineering, Data Analysis, Data Analytics, Data Visualization, Data, Data Build Tool (dbt), Machine Learning, Team Management, Stakeholder Engagement, Serverless


RStudio Shiny, Hadoop, Spark


Terraform, Git, GitHub, Tableau, Microsoft Power BI, Sqoop


Linux, RStudio, AWS Lambda, Amazon Web Services (AWS), Visual Studio Code (VS Code), Apache Kafka, Databricks, Azure