Notes On Using
Data Science & Machine Learning
To Fight For Something That Matters
I am a data scientist with a decade of experience applying statistical learning, artificial intelligence, and software engineering to political, social, and humanitarian efforts -- from election monitoring to disaster relief.
Learning machine learning? Check out my Machine Learning Flashcards or my book, Machine Learning With Python Cookbook.
Machine Learning
Basics
- Loading Features From Dictionaries
- Loading scikit-learn's Boston Housing Dataset
- Loading scikit-learn's Digits Dataset
- Loading scikit-learn's Iris Dataset
- Make Simulated Data For Classification
- Make Simulated Data For Clustering
- Make Simulated Data For Regression
- Perceptron In Scikit
- Saving Machine Learning Models
Vectors, Matrices, And Arrays
- Transpose A Vector Or Matrix
- Selecting Elements In An Array
- Reshape An Array
- Invert A Matrix
- Getting The Diagonal Of A Matrix
- Flatten A Matrix
- Find The Rank Of A Matrix
- Find The Maximum And Minimum
- Describe An Array
- Create A Vector
- Create A Sparse Matrix
- Create A Matrix
- Converting A Dictionary Into A Matrix
- Calculate The Trace Of A Matrix
- Calculate The Determinant Of A Matrix
- Calculate The Average, Variance, And Standard Deviation
- Calculate Dot Product Of Two Vectors
- Apply Operations To Elements
- Adding And Subtracting Matrices
Preprocessing Structured Data
- Convert Pandas Categorical Data For Scikit-Learn
- Delete Observations With Missing Values
- Deleting Missing Values
- Detecting Outliers
- Discretize Features
- Encoding Ordinal Categorical Features
- Handling Imbalanced Classes With Downsampling
- Handling Imbalanced Classes With Upsampling
- Handling Outliers
- Impute Missing Values With Means
- Imputing Missing Class Labels
- Imputing Missing Class Labels Using k-Nearest Neighbors
- Normalizing Observations
- One-Hot Encode Features With Multiple Labels
- One-Hot Encode Nominal Categorical Features
- Preprocessing Categorical Features
- Preprocessing Iris Data
- Rescale A Feature
- Standardize A Feature
Preprocessing Images
Preprocessing Dates And Times
- Break Up Dates And Times Into Multiple Features
- Calculate Difference Between Dates And Times
- Convert Strings To Dates
- Convert pandas Columns Time Zone
- Encode Days Of The Week
- Handling Missing Values In Time Series
- Handling Time Zones
- Lag A Time Feature
- Rolling Time Window
- Select Date And Time Ranges
Feature Engineering
- Dimensionality Reduction On Sparse Feature Matrix
- Dimensionality Reduction With Kernel PCA
- Dimensionality Reduction With PCA
- Feature Extraction With PCA
- Group Observations Using K-Means Clustering
- Selecting The Best Number Of Components For LDA
- Selecting The Best Number Of Components For TSVD
- Using Linear Discriminant Analysis For Dimensionality Reduction
Model Evaluation
- Accuracy
- Create Baseline Classification Model
- Create Baseline Regression Model
- Cross Validation Pipeline
- Cross Validation With Parameter Tuning Using Grid Search
- Cross-Validation
- Custom Performance Metric
- F1 Score
- Generate Text Reports On Performance
- Nested Cross Validation
- Plot The Learning Curve
- Plot The Receiving Operating Characteristic Curve
- Plot The Validation Curve
- Precision
- Recall
- Split Data Into Training And Test Sets
Trees And Forests
- Adaboost Classifier
- Decision Tree Classifier
- Decision Tree Regression
- Feature Importance
- Feature Selection Using Random Forest
- Handle Imbalanced Classes In Random Forest
- Random Forest Classifier
- Random Forest Classifier Example
- Random Forest Regression
- Select Important Features In Random Forest
- Titanic Competition With Random Forest
- Visualize A Decision Tree
Deep Learning
Keras
- Adding Dropout
- Convolutional Neural Network
- Feedforward Neural Network For Binary Classification
- Feedforward Neural Network For Multiclass Classification
- Feedforward Neural Networks For Regression
- LSTM Recurrent Neural Network
- Neural Network Early Stopping
- Neural Network Weight Regularization
- Preprocessing Data For Neural Networks
- Save Model Training Progress
- Tuning Neural Network Hyperparameters
- Visualize Loss History
- Visualize Neural Network Architecutre
- Visualize Performance History
- k-Fold Cross-Validating Neural Networks
Python
Basics
- Add Padding Around String
- All Combinations For A List Of Objects
- Apply Operations Over Items In A List
- Applying Functions To List Items
- Arithmetic Basics
- Assignment Operators
- Basic Operations With NumPy Array
- Breaking Up String Variables
- Brute Force D20 Roll Simulator
- Cartesian Product
- Chain Together Lists
- Cleaning Text
- Compare Two Dictionaries
- Concurrent Processing
- Continue And Break Loops
- Convert HTML Characters To Strings
- Converting Strings To Datetime
- Create A New File Then Write To It
- Create A Temporary File
- Data Structure Basics
- Date And Time Basics
- Dictionary Basics
- Display JSON
- Display Scientific Notation As Floats
- Exiting A Loop
- Find The Max Value In A Dictionary
- Flatten Lists Of Lists
- For Loop
- Formatting Numbers
- Function Annotation Examples
- Function Basics
- Functions Vs. Generators
- Generating Random Numbers With NumPy
- Generator Expressions
- Hard Wrapping Text
- How To Use Default Dicts
- If Else On Any Or All Elements
- Indexing And Slicing NumPy Arrays
- Indexing And Slicing NumPy Arrays
- Iterate An Ifelse Over A List
- Iterate Over Multiple Lists Simultaneously
- Iterating Over Dictionary Keys
- Lambda Functions
- List All Files Of Certain Type In A Directory
- Logical Operations
- Looping Over Two Lists
- Mathematical Operations
- Mocking Functions
- Nested For Loops Using List Comprehension
- Nesting Lists
- Numpy Array Basics
- Parallel Processing
- Partial Function Applications
- Priority Queues
- Queues And Stacks
- Recursive Functions
- Scheduling Jobs In The Future
- Select Random Element From A List
- Selecting Items In A List With Filters
- Set The Color Of A Matplotlib Plot
- Sort A List Of Names By Last Name
- Sort A List Of Strings By Length
- Store API Credentials For Open Source Projects
- String Formatting
- String Indexing
- String Operations
- Swapping Variable Values
- Try, Except, and Finally
- Unpacking A Tuple
- Unpacking Function Arguments
- Use Command Line Arguments In A Function
- Using Named Tuples To Store Data
- any(), all(), max(), min(), sum()
- if and if else
- repr vs. str
- while Statement
Data Wrangling
- Apply Functions By Group In Pandas
- Apply Operations To Groups In Pandas
- Applying Operations Over pandas Dataframes
- Assign A New Column To A Pandas DataFrame
- Break A List Into N-Sized Chunks
- Breaking Up A String Into Columns Using Regex In pandas
- Columns Shared By Two Data Frames
- Construct A Dictionary From Multiple Lists
- Convert A CSV Into Python Code To Recreate It
- Convert A Categorical Variable Into Dummy Variables
- Convert A Categorical Variable Into Dummy Variables
- Convert A String Categorical Variable To A Numeric Variable
- Convert A Variable To A Time Variable In pandas
- Count Values In Pandas Dataframe
- Create A Pipeline In Pandas
- Create A pandas Column With A For Loop
- Create Counts Of Items
- Create a Column Based on a Conditional in pandas
- Creating Lists From Dictionary Keys And Values
- Crosstabs In pandas
- Delete Duplicates In pandas
- Descriptive Statistics For pandas Dataframe
- Dropping Rows And Columns In pandas Dataframe
- Enumerate A List
- Expand Cells Containing Lists Into Their Own Variables In Pandas
- Filter pandas Dataframes
- Find Largest Value In A Dataframe Column
- Find Unique Values In Pandas Dataframes
- Geocoding And Reverse Geocoding
- Geolocate A City And Country
- Geolocate A City Or Country
- Group A Time Series With pandas
- Group Data By Time
- Group Pandas Data By Hour Of The Day
- Grouping Rows In pandas
- Hierarchical Data In pandas
- Join And Merge Pandas Dataframe
- List Unique Values In A pandas Column
- Load A JSON File Into Pandas
- Load An Excel File Into Pandas
- Load Excel Spreadsheet As pandas Dataframe
- Loading A CSV Into pandas
- Long To Wide Format
- Lower Case Column Names In Pandas Dataframe
- Make New Columns Using Functions
- Map External Values To Dataframe Values in pandas
- Missing Data In pandas Dataframes
- Moving Averages In pandas
- Normalize A Column In pandas
- Pivot Tables In pandas
- Quickly Change A Column Of Strings In Pandas
- Random Sampling Dataframe
- Ranking Rows Of Pandas Dataframes
- Regular Expression Basics
- Regular Expression By Example
- Reindexing pandas Series And Dataframes
- Rename Column Headers In pandas
- Rename Multiple pandas Dataframe Column Names
- Replacing Values In pandas
- Saving A pandas Dataframe As A CSV
- Search A pandas Column For A Value
- Select Rows When Columns Contain Certain Values
- Select Rows With A Certain Value
- Select Rows With Multiple Filters
- Selecting pandas DataFrame Rows Based On Conditions
- Simple Example Dataframes In pandas
- Sorting Rows In pandas Dataframes
- Split Lat/Long Coordinate Variables Into Separate Variables
- Streaming Data Pipeline
- String Munging In Dataframe
- Using List Comprehensions With pandas
- Using Seaborn To Visualize A pandas Dataframe
- pandas Data Structures
- pandas Time Series Basics
Data Visualization
- Back To Back Bar Plot In MatPlotLib
- Bar Plot In MatPlotLib
- Color Palettes in Seaborn
- Creating A Time Series Plot With Seaborn And pandas
- Creating Scatterplots With Seaborn
- Group Bar Plot In MatPlotLib
- Histograms In MatPlotLib
- Making A Matplotlib Scatterplot From A Pandas Dataframe
- Matplotlib, A Simple Example
- Pie Chart In MatPlotLib
- Scatterplot In MatPlotLib
- Stacked Percentage Bar Plot In MatPlotLib
Logging
Statistics
Basics
Scala
- Break A Sequence Into Groups
- Change Data Type
- Chunk Sequence In Equal Sized Groups
- Compare Two Floats
- Create A Range
- Extract Substrings Using Regex
- Filter A Sequence
- Find Largest Key Or Value In A Map
- Flatten Sequence Of Sequences
- For Loop A Map
- For Looping
- Format Numbers As Currency
- If Else
- Increment And Decrement Numbers
- Insert Variables Into Strings
- Iterate Over A Map
- Loop A Collection
- Make Numbers Pretty
- Mapping A Function To A Collection
- Matching Conditions
- Mutable Maps
- N Dimension Arrays
- Partial Functions
- Random Integer Between Two Values
- Replacing Parts Of Strings
- Search A Map
- Search Strings
- Search Strings Using Regex
- Set Operations On Sequences
- Sorting Sequences
- Split Strings
- Try, Catch, Finally
- Variables And Values
- Zip Together Two Lists
Regular Expressions
- Match A Symbol
- Match A Unicode Character
- Match A Word
- Match Any Character
- Match Any Of A List Of Characters
- Match Any Of A Series Of Options
- Match Any Of A Series Of Words
- Match Dates
- Match Email Addresses
- Match Exact Text
- Match Integers Of Any Length
- Match Text Between HTML Tags
- Match Times
- Match URLs
- Match US Phone Numbers
- Match US and UK Spellings
- Match Words With A Certain Ending
- Match ZIP Codes
Snowflake
Rows
Merge And Join
Tables
- Add Column
- Add Comment To Column
- Create Or Replace Table
- Create Table
- Create Table From Query
- Create Table If It Doesn't Already Exist
- Create Table With Column And Table Comments
- Create Temporary Table
- Delete A Table
- Describe A Table
- Drop Column
- Query DESCRIBE TABLE like a table
- Rename Column
- Rename Table
- Swap Two Tables
- Undelete A Table
- View A Column's Comments
- View A Table's Comments
Text
Numeric
Dates
Databases
Other
PostgreSQL
Basics
- Apply Operation To Column
- Compare Values To Subquery
- Copy Rows From One Table To Another
- Count Rows
- Count Unique Values
- Create Column Index
- Create PostgreSQL Database With Python
- Create Subquery
- Create View
- Delete View
- Examine A Query
- Group Rows
- Group Rows With Conditions
- If Else
- List Index Columns
- List Tables In Database
- Rename Columns In Views
- Replace Missing Values
- Retrieve Only A Few Rows
- Retrieve Random Subset Of Rows
- Retrieve Row
- Retrieve Rows Based On Condition
- Retrieve Rows Based On Multiple Condition
- Retrieve Subset Of Columns
- Retrieving Missing Values
- Save Queries As Variables
- Select Highest Value In Each Group
- Select Values Between Two Values
- Sort Rows
- Sort Rows In Groups
- Test If Rows Exist In Subquery
- Use Column Aliases With Where Clause
- Value Matches Element Of A List
- View Unique Values
Add, Delete, Change Rows
- Add Column
- Change Values
- Create Column Aliases
- Create Column Conditional On Another Column
- Create Column Of Values
- Create Primary Key
- Delete All Rows
- Delete Duplicates
- Delete Primary Key
- Delete Rows
- Delete Rows That Don't Exist In Another Table
- Export To CSV
- Import CSV
- Insert Rows
- Update Rows Based On Another Table
Mathematics
AWS
Computer Science
Linux Command Line
Basics
- Archive And Unarchive Files
- Change Permissions
- Changing Directories
- Check Current Date And Time
- Copy Files And Directories
- Create Command
- Create Directory
- Create File
- Create Sequential List Of Files And Directories
- Create Symbolic Links
- Delete Files And Directories
- Delete Files And Directories In Current Directory
- Exit Terminal Session
- Get Help With A Command
- Get Information On A File
- List Avaliable Commands
- List The Contents Of A Directory
- Move Files And Directories
- Multiple Commands On One Line
- Ping Website
- Rename File
- See Disk Drive Space
- See Free Memory
- See Who Is Logged Into A System
- Select Files Based On Filename
- Synchronize Files And Directories
- Track Route Of Network Traffic
- View A File's Type
- View A Text File's Contents
- View Current Working Directory
- View First And Last Parts Of Files
- Zip And Unzip Directories
- Zip And Unzip Files