add table reducer
This commit is contained in:
ryan
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import { parseCSV } from './processTableData';
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import { reduceTableData } from './tableReducer';
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describe('Table Reducer', () => {
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it('should calculate average', () => {
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const table = parseCSV('a,b,c\n1,2,3\n4,5,6');
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const reduced = reduceTableData(table, {
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stats: ['last'],
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});
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expect(reduced.length).toBe(1);
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expect(reduced[0].rows.length).toBe(1);
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expect(reduced[0].rows[0]).toEqual(table.rows[1]);
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console.log('REDUCE', reduced[0].rows);
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});
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});
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@@ -0,0 +1,237 @@
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// Libraries
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import isNumber from 'lodash/isNumber';
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import { TableData, NullValueMode } from '../types/index';
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/** Reduce each column in a table to a single value */
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export type TableReducer = (
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data: TableData,
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columnIndexes: number[],
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ignoreNulls: boolean,
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nullAsZero: boolean
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) => any[];
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/** Information about the reducing(stats) functions */
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export interface TableReducerInfo {
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key: string;
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name: string;
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description: string;
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standard: boolean; // The most common stats can all be calculated in a single pass
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reducer?: TableReducer;
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alias?: string; // optional secondary key. 'avg' vs 'mean'
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}
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/** Get a list of the known reducing functions */
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export function getTableReducers(): TableReducerInfo[] {
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return reducers;
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}
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export interface TableReducerOptions {
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columnIndexes?: number[];
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nullValueMode?: NullValueMode;
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stats: string[]; // The stats to calculate
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}
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export function reduceTableData(data: TableData, options: TableReducerOptions): TableData[] {
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if (registry == null) {
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registry = new Map<string, TableReducerInfo>();
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reducers.forEach(calc => {
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registry!.set(calc.key, calc);
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if (calc.alias) {
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registry!.set(calc.alias, calc);
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}
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});
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}
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const indexes = verifyColumns(data, options);
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const columns = indexes.map(v => data.columns[v]);
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const ignoreNulls = options.nullValueMode === NullValueMode.Ignore;
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const nullAsZero = options.nullValueMode === NullValueMode.AsZero;
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const queue = options.stats.map(key => {
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const c = registry!.get(key);
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if (!c) {
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throw new Error('Unknown stats calculator: ' + key);
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}
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return c;
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});
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// Avoid the standard calculator if possible
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if (queue.length === 1 && queue[0].reducer) {
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return [
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{
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columns,
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rows: [queue[0].reducer(data, indexes, ignoreNulls, nullAsZero)],
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type: 'table',
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columnMap: {},
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},
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];
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}
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// For now everything can use the standard stats
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const standard = standardStatsReducer(data, indexes, ignoreNulls, nullAsZero);
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return queue.map(calc => {
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const values = calc.standard
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? standard.map((s: any) => s[calc.key])
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: calc.reducer!(data, indexes, ignoreNulls, nullAsZero);
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return {
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columns,
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rows: [values],
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type: 'table',
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columnMap: {},
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};
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});
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}
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// ------------------------------------------------------------------------------
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//
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// No Exported symbols below here.
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//
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// ------------------------------------------------------------------------------
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/**
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* This will return an array of valid indexes and throw an error if invalid request
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*/
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function verifyColumns(data: TableData, options: TableReducerOptions): number[] {
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const { columnIndexes } = options;
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if (!columnIndexes) {
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return data.columns.map((v, idx) => idx);
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}
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columnIndexes.forEach(v => {
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if (v < 0 || v >= data.columns.length) {
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throw new Error('Invalid column selection: ' + v);
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}
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});
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return columnIndexes;
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}
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interface StandardStats {
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sum: number | null; // total
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max: number | null;
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min: number | null;
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logmin: number;
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mean: number | null; // avg
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last: any; // current
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first: any;
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count: number;
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nonNullCount: number;
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range: number | null;
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diff: number | null;
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allIsZero: boolean;
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allIsNull: boolean;
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}
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const reducers: TableReducerInfo[] = [
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{ key: 'sum', alias: 'total', name: 'Total', description: 'The sum of all values', standard: true },
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{ key: 'min', name: 'Min', description: 'Minimum Value', standard: true },
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{ key: 'max', name: 'Max', description: 'Maximum Value', standard: true },
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{ key: 'mean', name: 'Mean', description: 'Average Value', standard: true, alias: 'avg' },
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{ key: 'first', name: 'First', description: 'First Value', standard: true },
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{ key: 'last', name: 'Last', description: 'Last Value (current)', standard: true, alias: 'current' },
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{ key: 'count', name: 'Count', description: 'Value Count', standard: true },
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{ key: 'range', name: 'Range', description: 'Difference between minimum and maximum values', standard: true },
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{ key: 'diff', name: 'Difference', description: 'Difference between first and last values', standard: true },
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];
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let registry: Map<string, TableReducerInfo> | null = null;
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function standardStatsReducer(
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data: TableData,
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columnIndexes: number[],
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ignoreNulls: boolean,
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nullAsZero: boolean
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): StandardStats[] {
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const column = columnIndexes.map(idx => {
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return {
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sum: 0,
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max: -Number.MAX_VALUE,
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min: Number.MAX_VALUE,
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logmin: Number.MAX_VALUE,
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mean: null,
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last: null,
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first: null,
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count: 0,
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nonNullCount: 0,
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allIsNull: true,
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allIsZero: false,
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range: null,
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diff: null,
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} as StandardStats;
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});
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for (let i = 0; i < data.rows.length; i++) {
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for (let x = 0; x < column.length; x++) {
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const stats = column[x];
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let currentValue = data.rows[i][x];
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if (currentValue === null) {
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if (ignoreNulls) {
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continue;
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}
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if (nullAsZero) {
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currentValue = 0;
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}
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}
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if (stats.first === null) {
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stats.first = currentValue;
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}
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if (currentValue !== null) {
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stats.last = currentValue;
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if (isNumber(currentValue)) {
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stats.sum! += currentValue;
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stats.allIsNull = false;
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stats.nonNullCount++;
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}
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if (currentValue > stats.max!) {
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stats.max = currentValue;
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}
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if (currentValue < stats.min!) {
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stats.min = currentValue;
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}
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if (currentValue < stats.logmin && currentValue > 0) {
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stats.logmin = currentValue;
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}
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if (currentValue !== 0) {
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stats.allIsZero = false;
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}
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}
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}
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}
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for (let x = 0; x < column.length; x++) {
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const stats = column[x];
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if (stats.max === -Number.MAX_VALUE) {
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stats.max = null;
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}
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if (stats.min === Number.MAX_VALUE) {
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stats.min = null;
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}
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if (stats.nonNullCount > 0) {
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stats.mean = stats.sum! / stats.nonNullCount;
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}
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if (stats.max !== null && stats.min !== null) {
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stats.range = stats.max - stats.min;
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}
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if (stats.first !== null && stats.last !== null) {
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if (isNumber(stats.first) && isNumber(stats.last)) {
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stats.diff = stats.last - stats.first;
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}
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}
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}
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return column;
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}
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