@langchain/core
Version:
Core LangChain.js abstractions and schemas
151 lines (150 loc) • 5.43 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.LengthBasedExampleSelector = void 0;
const base_js_1 = require("./base.cjs");
/**
* Calculates the length of a text based on the number of words and lines.
*/
function getLengthBased(text) {
return text.split(/\n| /).length;
}
/**
* A specialized example selector that selects examples based on their
* length, ensuring that the total length of the selected examples does
* not exceed a specified maximum length.
* @example
* ```typescript
* const exampleSelector = new LengthBasedExampleSelector(
* [
* { input: "happy", output: "sad" },
* { input: "tall", output: "short" },
* { input: "energetic", output: "lethargic" },
* { input: "sunny", output: "gloomy" },
* { input: "windy", output: "calm" },
* ],
* {
* examplePrompt: new PromptTemplate({
* inputVariables: ["input", "output"],
* template: "Input: {input}\nOutput: {output}",
* }),
* maxLength: 25,
* },
* );
* const dynamicPrompt = new FewShotPromptTemplate({
* exampleSelector,
* examplePrompt: new PromptTemplate({
* inputVariables: ["input", "output"],
* template: "Input: {input}\nOutput: {output}",
* }),
* prefix: "Give the antonym of every input",
* suffix: "Input: {adjective}\nOutput:",
* inputVariables: ["adjective"],
* });
* console.log(dynamicPrompt.format({ adjective: "big" }));
* console.log(
* dynamicPrompt.format({
* adjective:
* "big and huge and massive and large and gigantic and tall and much much much much much bigger than everything else",
* }),
* );
* ```
*/
class LengthBasedExampleSelector extends base_js_1.BaseExampleSelector {
constructor(data) {
super(data);
Object.defineProperty(this, "examples", {
enumerable: true,
configurable: true,
writable: true,
value: []
});
Object.defineProperty(this, "examplePrompt", {
enumerable: true,
configurable: true,
writable: true,
value: void 0
});
Object.defineProperty(this, "getTextLength", {
enumerable: true,
configurable: true,
writable: true,
value: getLengthBased
});
Object.defineProperty(this, "maxLength", {
enumerable: true,
configurable: true,
writable: true,
value: 2048
});
Object.defineProperty(this, "exampleTextLengths", {
enumerable: true,
configurable: true,
writable: true,
value: []
});
this.examplePrompt = data.examplePrompt;
this.maxLength = data.maxLength ?? 2048;
this.getTextLength = data.getTextLength ?? getLengthBased;
}
/**
* Adds an example to the list of examples and calculates its length.
* @param example The example to be added.
* @returns Promise that resolves when the example has been added and its length calculated.
*/
async addExample(example) {
this.examples.push(example);
const stringExample = await this.examplePrompt.format(example);
this.exampleTextLengths.push(this.getTextLength(stringExample));
}
/**
* Calculates the lengths of the examples.
* @param v Array of lengths of the examples.
* @param values Instance of LengthBasedExampleSelector.
* @returns Promise that resolves with an array of lengths of the examples.
*/
async calculateExampleTextLengths(v, values) {
if (v.length > 0) {
return v;
}
const { examples, examplePrompt } = values;
const stringExamples = await Promise.all(examples.map((eg) => examplePrompt.format(eg)));
return stringExamples.map((eg) => this.getTextLength(eg));
}
/**
* Selects examples until the total length of the selected examples
* reaches the maxLength.
* @param inputVariables The input variables for the examples.
* @returns Promise that resolves with an array of selected examples.
*/
async selectExamples(inputVariables) {
const inputs = Object.values(inputVariables).join(" ");
let remainingLength = this.maxLength - this.getTextLength(inputs);
let i = 0;
const examples = [];
while (remainingLength > 0 && i < this.examples.length) {
const newLength = remainingLength - this.exampleTextLengths[i];
if (newLength < 0) {
break;
}
else {
examples.push(this.examples[i]);
remainingLength = newLength;
}
i += 1;
}
return examples;
}
/**
* Creates a new instance of LengthBasedExampleSelector and adds a list of
* examples to it.
* @param examples Array of examples to be added.
* @param args Input parameters for the LengthBasedExampleSelector.
* @returns Promise that resolves with a new instance of LengthBasedExampleSelector with the examples added.
*/
static async fromExamples(examples, args) {
const selector = new LengthBasedExampleSelector(args);
await Promise.all(examples.map((eg) => selector.addExample(eg)));
return selector;
}
}
exports.LengthBasedExampleSelector = LengthBasedExampleSelector;