DataFrame Basics
DataFrame properties, column access, and TypeScript integration. Learn the fundamentals before diving into data operations.
1. DataFrame Properties
Get fundamental information about your DataFrame structure
You can check basic properties like row count, column names, and print the entire DataFrame to see your data in a clean table format.
import { createDataFrame, stats as s } from "@tidy-ts/dataframe";
const jediKnights = createDataFrame([
{ id: 1, name: "Luke Skywalker", species: "Human", mass: 77, height: 172 },
{ id: 2, name: "Yoda", species: "Unknown", mass: 17, height: 66 },
{ id: 3, name: "Obi-Wan Kenobi", species: "Human", mass: 77, height: 182 },
]);
// Get basic properties
const numberOfRows = jediKnights.nrows();
const numberOfColumns = jediKnights.ncols();
const columnNames = jediKnights.columns();
const isEmpty = jediKnights.isEmpty();
// Print the DataFrame to the console
jediKnights.print("Jedi Knights DataFrame:");
// Print() is a chainable method that returns the DataFrame to allow for chaining.
// This gives an easy way to see intermedite results of a chain of operations.
const result = jediKnights
.print("Jedi Knights DataFrame before mutation:")
.mutate({
doubleMass: (r) => r.mass * 2,
})
.print("Jedi Knights DataFrame after mutation:");import { createDataFrame, stats as s } from "@tidy-ts/dataframe";
const jediKnights = createDataFrame([
{ id: 1, name: "Luke Skywalker", species: "Human", mass: 77, height: 172 },
{ id: 2, name: "Yoda", species: "Unknown", mass: 17, height: 66 },
{ id: 3, name: "Obi-Wan Kenobi", species: "Human", mass: 77, height: 182 },
]);
// Get basic properties
const numberOfRows = jediKnights.nrows();
const numberOfColumns = jediKnights.ncols();
const columnNames = jediKnights.columns();
const isEmpty = jediKnights.isEmpty();
// Print the DataFrame to the console
jediKnights.print("Jedi Knights DataFrame:");
// Print() is a chainable method that returns the DataFrame to allow for chaining.
// This gives an easy way to see intermedite results of a chain of operations.
const result = jediKnights
.print("Jedi Knights DataFrame before mutation:")
.mutate({
doubleMass: (r) => r.mass * 2,
})
.print("Jedi Knights DataFrame after mutation:");2. Basic Column Access
Access entire columns as typed arrays
The easiest way to access the raw data from any column is using dot notation. This returns a readonly array (to prevent accidental DataFrame mutations) and can be used with any JavaScript array method.
// Get all values from a column - TypeScript knows the exact types
const names = jediKnights.name; // readonly string[] - all names
const masses = jediKnights.mass; // readonly number[] - all masses
const species = jediKnights.species; // readonly string[] - all species
console.log("All names:", names);
console.log("All masses:", masses);
console.log("Unique species:", s.unique(species));
// Use with any array function for quick analysis
const avgMass = masses.reduce((sum, mass) => sum + mass, 0) / masses.length;
const maxHeight = Math.max(...jediKnights.height);
// or use the stats module
const avgMassTidy = s.mean(masses);
const maxHeightTidy = s.max(jediKnights.height);
console.log("Average mass:", avgMass);
console.log("Max height:", maxHeight);
console.log("Tidy Average mass:", avgMassTidy);
console.log("Tidy Max height:", maxHeightTidy);// Get all values from a column - TypeScript knows the exact types
const names = jediKnights.name; // readonly string[] - all names
const masses = jediKnights.mass; // readonly number[] - all masses
const species = jediKnights.species; // readonly string[] - all species
console.log("All names:", names);
console.log("All masses:", masses);
console.log("Unique species:", s.unique(species));
// Use with any array function for quick analysis
const avgMass = masses.reduce((sum, mass) => sum + mass, 0) / masses.length;
const maxHeight = Math.max(...jediKnights.height);
// or use the stats module
const avgMassTidy = s.mean(masses);
const maxHeightTidy = s.max(jediKnights.height);
console.log("Average mass:", avgMass);
console.log("Max height:", maxHeight);
console.log("Tidy Average mass:", avgMassTidy);
console.log("Tidy Max height:", maxHeightTidy);3. Extract Methods
The extract(), extractHead(), extractTail(), extractNth(), or extractSample() methods give an easy, chainable way to get mutable data out of a DataFrame. These values are copies and won't have any effect on the original DataFrame.
// Basic extract - get all values (mutable copy)
const allNames = jediKnights.extract("name");
console.log("All names:", allNames);
// Extract specific positions
const firstJedi = jediKnights.extractHead("name", 1); // Single value
const firstTwo = jediKnights.extractHead("name", 2); // Array of 2 values
const lastJedi = jediKnights.extractTail("name", 1); // Single value
const thirdJedi = jediKnights.extractNth("name", 2); // Value at index 2
console.log("First Jedi:", firstJedi);
console.log("First two:", firstTwo);
console.log("Last Jedi:", lastJedi);
console.log("Third Jedi:", thirdJedi);
// Random sampling
const randomJedi = jediKnights.extractSample("name", 2);
console.log("Random sample:", randomJedi);// Basic extract - get all values (mutable copy)
const allNames = jediKnights.extract("name");
console.log("All names:", allNames);
// Extract specific positions
const firstJedi = jediKnights.extractHead("name", 1); // Single value
const firstTwo = jediKnights.extractHead("name", 2); // Array of 2 values
const lastJedi = jediKnights.extractTail("name", 1); // Single value
const thirdJedi = jediKnights.extractNth("name", 2); // Value at index 2
console.log("First Jedi:", firstJedi);
console.log("First two:", firstTwo);
console.log("Last Jedi:", lastJedi);
console.log("Third Jedi:", thirdJedi);
// Random sampling
const randomJedi = jediKnights.extractSample("name", 2);
console.log("Random sample:", randomJedi);