data-centric apps
problems to solve
Piotr Lewandowski
but what is data-centric?
- architecture
- database plays crucial role
- SQL / R / MatLab
I want to build an app...
... that will look for
productive music
we need data
- aggregation
- analysis
- visualization
Aggregation
Step 1
- fail safe
- repeatable
- independent
Data providers
last.fm API
RescueTime
- music I listen
- tracks & albums data
- duration
- categories
- activity I do
- classify productivity
Data providers
problems
- Limits
- Authentication problems
- Timeouts
- Remember to retry request
- Broken data
Copy all the data
to your database
aggregation is long process
no reason to do it twice
data analysis
Step 2
Data fusion
Proces of integration data from multiple sources
Matching
Activities
Music
- 10:05 - IDE
- 10:19 - Facebook
- 10:27 - YouTube
- 10:37 - IDE
- 10:03 - Jazz
- 10:09 - Rock
- 10:17 - Soul
- 10:24 - Smooth
- 10:33 - Rock
Prediction
machine learning
- Lots of data
- Problem with validation data
- Asking the right question
- Garbage input - Garbage output
Tools
Python FTW
- designed for network apps
- event loop blocks heavy tasks
- lack of community support
Python libs
-
NumPy - matrix calculation
- SIMD - Single Input Multiple Data
- O(1) vs O(n^2)
- pandas - data structure
- scikit-learn - Machine learning alghoritms
-
matplotlib - graphs and plots
App flow
Aggregation
and data fusion
Analysis
Visualisation
Node.js
scikit-learn
(python)
chart / tables
(JavaScript)
database
last.fm + RescueTime
Visualisation
Step 3
It's not about excel anymore
Don't make people think
Start with the story
One dataset
many stories
There are three kinds of lies: lies, damned lies, and statistics
- popularised by Mark Twain
Do we need a team?
- Data scientist
- Developer
- Graphic designer
Student
Nope.