@tidyjs/tidy/dist/lib/vector/roll.js

Tidy up your data with JavaScript, inspired by dplyr and the tidyverse

'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

function roll(width, rollFn, options) {
  const {partial = false, align = "right"} = options != null ? options : {};
  const halfWidth = Math.floor(width / 2);
  return (items) => {
    return items.map((_, i) => {
      const endIndex = align === "right" ? i : align === "center" ? i + halfWidth : i + width - 1;
      if (!partial && (endIndex - width + 1 < 0 || endIndex >= items.length)) {
        return void 0;
      }
      const startIndex = Math.max(0, endIndex - width + 1);
      const itemsInWindow = items.slice(startIndex, endIndex + 1);
      return rollFn(itemsInWindow, endIndex);
    });
  };
}

exports.roll = roll;
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