Add practice exercise: matrix

config.json

@@ -202,6 +202,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "matrix",
+        "name": "Matrix",
+        "uuid": "6884edbe-4a2b-4415-8aa0-57c959b200c8",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "meetup",
         "name": "Meetup",

exercises/practice/matrix/.docs/instructions.append.md

@@ -0,0 +1,7 @@
+# SQLite-specific instructions
+
+## JSON documentation
+
+[JSON Functions And Operators][json-docs]
+
+[json-docs]: https://www.sqlite.org/json1.html

exercises/practice/matrix/.docs/instructions.md

@@ -0,0 +1,38 @@
+# Instructions
+
+Given a string representing a matrix of numbers, return the rows and columns of that matrix.
+
+So given a string with embedded newlines like:
+
+```text
+9 8 7
+5 3 2
+6 6 7
+```
+
+representing this matrix:
+
+```text
+    1  2  3
+  |---------
+1 | 9  8  7
+2 | 5  3  2
+3 | 6  6  7
+```
+
+your code should be able to spit out:
+
+- A list of the rows, reading each row left-to-right while moving top-to-bottom across the rows,
+- A list of the columns, reading each column top-to-bottom while moving from left-to-right.
+
+The rows for our example matrix:
+
+- 9, 8, 7
+- 5, 3, 2
+- 6, 6, 7
+
+And its columns:
+
+- 9, 5, 6
+- 8, 3, 6
+- 7, 2, 7

exercises/practice/matrix/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "jimmytty"
+  ],
+  "files": {
+    "solution": [
+      "matrix.sql"
+    ],
+    "test": [
+      "matrix_test.sql"
+    ],
+    "example": [
+      ".meta/example.sql"
+    ]
+  },
+  "blurb": "Given a string representing a matrix of numbers, return the rows and columns of that matrix.",
+  "source": "Exercise by the JumpstartLab team for students at The Turing School of Software and Design.",
+  "source_url": "https://turing.edu"
+}

exercises/practice/matrix/.meta/example.sql

@@ -0,0 +1,22 @@
+UPDATE matrix
+   SET result = (
+     SELECT j.value
+       FROM JSON_EACH(
+         PRINTF('[[%s]]', REPLACE(REPLACE(string, ' ', ','), CHAR(10), '],['))
+       ) j
+ WHERE j.key = "index" - 1
+   )
+ WHERE property = 'row'
+;
+
+UPDATE matrix
+   SET result = (
+     SELECT JSON_GROUP_ARRAY(
+       JSON_EXTRACT(j.value, PRINTF('$[%d]', "index" - 1))
+     )
+       FROM JSON_EACH(
+         PRINTF('[[%s]]', REPLACE(REPLACE(string, ' ', ','), CHAR(10), '],['))
+       ) j
+     )
+ WHERE property = 'column'
+;

exercises/practice/matrix/.meta/tests.toml

@@ -0,0 +1,34 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[ca733dab-9d85-4065-9ef6-a880a951dafd]
+description = "extract row from one number matrix"
+
+[5c93ec93-80e1-4268-9fc2-63bc7d23385c]
+description = "can extract row"
+
+[2f1aad89-ad0f-4bd2-9919-99a8bff0305a]
+description = "extract row where numbers have different widths"
+
+[68f7f6ba-57e2-4e87-82d0-ad09889b5204]
+description = "can extract row from non-square matrix with no corresponding column"
+
+[e8c74391-c93b-4aed-8bfe-f3c9beb89ebb]
+description = "extract column from one number matrix"
+
+[7136bdbd-b3dc-48c4-a10c-8230976d3727]
+description = "can extract column"
+
+[ad64f8d7-bba6-4182-8adf-0c14de3d0eca]
+description = "can extract column from non-square matrix with no corresponding row"
+
+[9eddfa5c-8474-440e-ae0a-f018c2a0dd89]
+description = "extract column where numbers have different widths"

exercises/practice/matrix/create_fixture.sql

@@ -0,0 +1,13 @@
+DROP TABLE IF EXISTS matrix;
+CREATE TABLE matrix (
+    property TEXT    NOT NULL,
+    string   TEXT    NOT NULL,
+    "index"  INTEGER NOT NULL,
+    result   TEXT               -- json array of integers
+);
+
+.mode csv
+.import ./data.csv matrix
+
+UPDATE matrix SET result = NULL;
+UPDATE matrix SET string = REPLACE(string, '\n', CHAR(10));

exercises/practice/matrix/create_test_table.sql

@@ -0,0 +1,30 @@
+DROP TABLE IF EXISTS tests;
+CREATE TABLE IF NOT EXISTS tests (
+    -- uuid and description are taken from the test.toml file
+    uuid TEXT PRIMARY KEY,
+    description TEXT NOT NULL,
+    -- The following section is needed by the online test-runner
+    status TEXT DEFAULT 'fail',
+    message TEXT,
+    output TEXT,
+    test_code TEXT,
+    task_id INTEGER DEFAULT NULL,
+    -- Here are columns for the actual tests
+    property TEXT NOT NULL,
+    string TEXT NOT NULL,
+    "index" INTEGER NOT NULL,
+    expected TEXT NOT NULL      -- json array of integers
+);
+
+INSERT INTO tests (uuid, description, property, string, "index", expected)
+VALUES
+        ('ca733dab-9d85-4065-9ef6-a880a951dafd', 'extract row from one number matrix', 'row', '1', 1, '[1]'),
+        ('5c93ec93-80e1-4268-9fc2-63bc7d23385c', 'can extract row', 'row', '1 2\n3 4', 2, '[3,4]'),
+        ('2f1aad89-ad0f-4bd2-9919-99a8bff0305a', 'extract row where numbers have different widths', 'row', '1 2\n10 20', 2, '[10,20]'),
+        ('68f7f6ba-57e2-4e87-82d0-ad09889b5204', 'can extract row from non-square matrix with no corresponding column', 'row', '1 2 3\n4 5 6\n7 8 9\n8 7 6', 4, '[8,7,6]'),
+        ('e8c74391-c93b-4aed-8bfe-f3c9beb89ebb', 'extract column from one number matrix', 'column', '1', 1, '[1]'),
+        ('7136bdbd-b3dc-48c4-a10c-8230976d3727', 'can extract column', 'column', '1 2 3\n4 5 6\n7 8 9', 3, '[3,6,9]'),
+        ('ad64f8d7-bba6-4182-8adf-0c14de3d0eca', 'can extract column from non-square matrix with no corresponding row', 'column', '1 2 3 4\n5 6 7 8\n9 8 7 6', 4, '[4,8,6]'),
+        ('9eddfa5c-8474-440e-ae0a-f018c2a0dd89', 'extract column where numbers have different widths', 'column', '89 1903 3\n18 3 1\n9 4 800', 2, '[1903,3,4]');
+
+UPDATE tests SET string = REPLACE(string, '\n', CHAR(10));

exercises/practice/matrix/data.csv

@@ -0,0 +1,8 @@
+"row","1",1,
+"row","1 2\n3 4",2,
+"row","1 2\n10 20",2,
+"row","1 2 3\n4 5 6\n7 8 9\n8 7 6",4,
+"column","1",1,
+"column","1 2 3\n4 5 6\n7 8 9",3,
+"column","1 2 3 4\n5 6 7 8\n9 8 7 6",4,
+"column","89 1903 3\n18 3 1\n9 4 800",2,

exercises/practice/matrix/matrix.sql

@@ -0,0 +1,9 @@
+-- Schema:
+-- CREATE TABLE matrix (
+--     string   TEXT    NOT NULL,  -- the matrix as a plain string
+--     property TEXT    NOT NULL,  -- either "row" or "column" which we want to extract
+--     "index"  INTEGER NOT NULL,  -- the row or column index to extract
+--     result   TEXT               -- json array of integers containing the row or column at the specified index
+-- );
+--
+-- Task: update the matrix table and set the result based on the property, string and index.

exercises/practice/matrix/matrix_test.sql

@@ -0,0 +1,40 @@
+-- Create database:
+.read ./create_fixture.sql
+
+-- Read user student solution and save any output as markdown in user_output.md:
+.mode markdown
+.output user_output.md
+.read ./matrix.sql
+.output
+
+-- Create a clean testing environment:
+.read ./create_test_table.sql
+
+-- Comparison of user input and the tests updates the status for each test:
+UPDATE tests
+SET status = 'pass'
+FROM (SELECT property, string, "index", result FROM matrix) AS actual
+WHERE (actual.property, actual.string, actual."index", JSON(actual.result)) = (tests.property, tests.string, tests."index", JSON(tests.expected));
+
+-- Update message for failed tests to give helpful information:
+UPDATE tests
+SET message = (
+    'Result for "'
+    || PRINTF('property=%s,string=%s,index=%d', tests.property, tests.string, tests."index")
+    || '"'
+    || ' is <' || COALESCE(actual.result, 'NULL')
+    || '> but should be <' || tests.expected || '>'
+)
+FROM (SELECT property, string, "index", result FROM matrix) AS actual
+WHERE (actual.property, actual.string, actual."index") = (tests.property, tests.string, tests."index") AND tests.status = 'fail';
+
+-- Save results to ./output.json (needed by the online test-runner)
+.mode json
+.once './output.json'
+SELECT description, status, message, output, test_code, task_id
+FROM tests;
+
+-- Display test results in readable form for the student:
+.mode table
+SELECT description, status, message
+FROM tests;