feat(lib): Support mapping a column to multiple columns (#189)

* feat(lib): Support mapping a column to multiple columns

Extremely useful for classification.

* test(lib): Resolve flattening test flakiness

* ci(config): Integrate with Mergeable

* ci(config): Integrate with Dependabot

* build(deps-dev): Fix security issues

* docs(lib): Add flatten to advanced usage example

Author: isair

.eslintrc.js

@@ -35,6 +35,7 @@ module.exports = {
         'newlines-between': 'always',
       },
     ],
+    'sonarjs/cognitive-complexity': ['error', 18],
   },
   overrides: [
     {

.github/dependabot.yml

@@ -0,0 +1,13 @@
+version: 2
+updates:
+# Fetch and update latest `npm` packages
+- package-ecosystem: npm
+  directory: '/'
+  schedule:
+    interval: daily
+    time: '00:00'
+  open-pull-requests-limit: 10
+  reviewers:
+    - isair
+  assignees:
+    - isair

.github/mergeable.yml

@@ -0,0 +1,36 @@
+version: 2
+mergeable:
+  - when: pull_request.*
+    validate:
+      - do: assignee
+        min:
+          count: 1
+      - do: approvals
+        min:
+          count: 1
+        block:
+          changes_requested: true
+      - do: title
+        must_include:
+          regex: '^[a-z]+\([a-z-]+\): [A-Z]{1}(.+)$'
+      - do: dependent
+        changed:
+          file: 'package.json'
+          required: ['package-lock.json']
+
+  - when: schedule.repository
+    validate:
+      - do: stale
+        days: 20
+        type: pull_request, issues
+    pass:
+      - do: comment
+        payload:
+          body: This is old. Is it still relevant?
+
+  - when: pull_request.*, pull_request_review.*, status.*, check_suite.*
+    name: 'Automatically merge pull requests once it passes all checks'
+    validate: []
+    pass:
+      - do: merge
+        merge_method: 'squash'

.github/workflows/check-pr.yml

@@ -65,8 +65,9 @@ const {
   labelColumns: ['temperature'],
   mappings: {
     height: (ft) => ft * 0.3048, // feet to meters
-    temperature: (f) => (f - 32) / 1.8, // fahrenheit to celsius
+    temperature: (f) => (f < 50 ? [1, 0] : [0, 1]), // cold or hot classification
   }, // Map values based on which column they are in before they are loaded into tensors.
+  flatten: ['temperature'], // Flattens the array result of a mapping so that each member is a new column.
   shuffle: true, // Pass true to shuffle with a fixed seed, or a string to use it as a seed for the shuffling.
   splitTest: true, // Splits your data in half. You can also provide a certain row count for the test data, or a percentage string (e.g. 10%).
   prependOnes: true, // Prepends a column of 1s to your features and testFeatures tensors, useful for linear regression.

README.md

@@ -0,0 +1 @@
+test,headers,should,fail

assets/csv/empty.csv

@@ -4,7 +4,7 @@ module.exports = [
   'github',
   'script',
   'deps',
-  'dev-deps',
+  'deps-dev',
   'asset',
   'lib',
   'release',