@jmparsons/ccxt
Version:
A JavaScript / Python / PHP cryptocurrency trading library with support for 100+ exchanges
228 lines (160 loc) • 5.83 kB
JavaScript
;
/* ------------------------------------------------------------------------ */
const { isObject, isNumber, isDictionary, isArray } = require ('./type')
/* ------------------------------------------------------------------------ */
const keys = Object.keys
, values = x => !isArray (x) // don't copy arrays if they're already arrays!
? Object.values (x)
: x
, index = x => new Set (values (x))
, extend = (...args) => Object.assign ({}, ...args) // NB: side-effect free
, clone = x => isArray (x)
? Array.from (x) // clones arrays
: extend (x) // clones objects
/* ------------------------------------------------------------------------ */
module.exports =
{ keys
, values
, extend
, clone
, index
, ordered: x => x // a stub to keep assoc keys in order (in JS it does nothing, it's mostly for Python)
, unique: x => Array.from (index (x))
/* ............................................. */
, inArray (needle, haystack) {
return haystack.includes (needle)
}
, toArray (object) {
return Object.values (object)
}
/* ............................................. */
, keysort (x, out = {}) {
for (const k of keys (x).sort ())
out[k] = x[k]
return out
}
/* ............................................. */
/*
Accepts a map/array of objects and a key name to be used as an index:
array = [
{ someKey: 'value1', anotherKey: 'anotherValue1' },
{ someKey: 'value2', anotherKey: 'anotherValue2' },
{ someKey: 'value3', anotherKey: 'anotherValue3' },
]
key = 'someKey'
Returns a map:
{
value1: { someKey: 'value1', anotherKey: 'anotherValue1' },
value2: { someKey: 'value2', anotherKey: 'anotherValue2' },
value3: { someKey: 'value3', anotherKey: 'anotherValue3' },
}
*/
, indexBy (x, k, out = {}) {
for (const v of values (x))
if (k in v)
out[v[k]] = v
return out
}
/* ............................................. */
/*
Accepts a map/array of objects and a key name to be used as a grouping parameter:
array = [
{ someKey: 'value1', anotherKey: 'anotherValue1' },
{ someKey: 'value1', anotherKey: 'anotherValue2' },
{ someKey: 'value3', anotherKey: 'anotherValue3' },
]
key = 'someKey'
Returns a map:
{
value1: [
{ someKey: 'value1', anotherKey: 'anotherValue1' },
{ someKey: 'value1', anotherKey: 'anotherValue2' },
]
value3: [
{ someKey: 'value3', anotherKey: 'anotherValue3' }
],
}
*/
, groupBy (x, k, out = {}) {
for (const v of values (x)) {
if (k in v) {
const p = v[k]
out[p] = out[p] || []
out[p].push (v)
}
}
return out
}
/* ............................................. */
/*
Accepts a map/array of objects, a key name and a key value to be used as a filter:
array = [
{ someKey: 'value1', anotherKey: 'anotherValue1' },
{ someKey: 'value2', anotherKey: 'anotherValue2' },
{ someKey: 'value3', anotherKey: 'anotherValue3' },
]
key = 'someKey'
value = 'value1'
Returns an array:
[
value1: { someKey: 'value1', anotherKey: 'anotherValue1' },
]
*/
, filterBy (x, k, value = undefined, out = []) {
for (const v of values (x))
if (v[k] === value)
out.push (v)
return out
}
/* ............................................. */
, sortBy: (array, // NB: MUTATES ARRAY!
key,
descending = false,
direction = descending ? -1 : 1) => array.sort ((a, b) =>
((a[key] < b[key]) ? -direction :
((a[key] > b[key]) ? direction : 0)))
/* ............................................. */
, flatten: function flatten (x, out = []) {
for (const v of x) {
if (isArray (v)) flatten (v, out)
else out.push (v)
}
return out
}
/* ............................................. */
, pluck: (x, k) => values (x)
.filter (v => k in v)
.map (v => v[k])
/* ............................................. */
, omit (x, ...args) {
const out = clone (x)
for (const k of args) {
if (isArray (k)) // omit (x, ['a', 'b'])
for (const kk of k)
delete out[kk]
else delete out[k] // omit (x, 'a', 'b')
}
return out
}
/* ............................................. */
, sum (...xs) {
const ns = xs.filter (isNumber) // leave only numbers
return (ns.length > 0)
? ns.reduce ((a, b) => a + b, 0)
: undefined
}
/* ............................................. */
, deepExtend: function deepExtend (...xs) {
let out = undefined
for (const x of xs) {
if (isDictionary (x)) {
if (!isObject (out))
out = {}
for (const k in x)
out[k] = deepExtend (out[k], x[k])
} else out = x
}
return out
}
/* ------------------------------------------------------------------------ */
}