Ease of Movement

Install and import#

npm install fintech-algorithms

import { easeOfMovement } from "fintech-algorithms/technical-indicators/volume-indicators/ease-of-movement";

Signature#

easeOfMovement(input)

Divides the typical-price change by a box ratio built from scaled volume over the bar range, then smooths that raw reading with a simple moving average.

Parameters#

Returns#

TopicResult

series holds raw, the unsmoothed reading, and value, its simple moving average over period. latest carries the last element of each. raw is null on the first bar and on any bar whose high equals its low or whose volume is 0; value needs a full window of non-null raw, so it starts later than raw. Both warm-ups are described below.

Warm-up#

The first 1 bar for `raw`; `period` bars for `value` (index 14 with the defaults) positions are null. ready_at is 1, driven by raw. Because a null inside the window restarts the average, any flat or zero-volume bar pushes value out by a further period bars.

Errors#

• When volume_scale is below 0.000001 or not a finite number — throws Error
• When period is not an integer of at least 2 — throws Error
• When a bar carries a negative volume — throws Error

Complexity: time O(n), space O(n).

Worked example#

executed Captured by running this function on the input its own test provides. Real output of real code — but not asserted against a published figure.

Input#

{
  "bars": [
    {
      "timestamp": "2024-01-02",
      "basis": "synthetic-unadjusted",
      "open": 100,
      "high": 101.45,
      "low": 98.695,
      "close": 100,
      "volume": 750000,
      "benchmark": 200
    },
    {
      "timestamp": "2024-01-03",
      "basis": "synthetic-unadjusted",
      "open": 101.49111452,
      "high": 103.38381693,
      "low": 100.05480022,
      "close": 101.78791214,
      "volume": 795117,
      "benchmark": 200.56326135
    },
    {
      "timestamp": "2024-01-04",
      "basis": "synthetic-unadjusted",
      "open": 102.45519048,
      "high": 104.6701838,
      "low": 100.91147007,
      "close": 102.9549389,
      "volume": 840234,
      "benchmark": 201.11020913
    }
  ],
  "parameters": {}
}

Call#

easeOfMovement(input)

Returns#

object with 9 fields: topic_id, title, state, ready, ready_at, series, latest, parameters, …

{
  "topic_id": "D07-F05-A12",
  "title": "Ease of Movement",
  "state": "calculated",
  "ready": true,
  "ready_at": 1,
  "series": {
    "raw": [
      null,
      7.09182670339273,
      4.935760375263474,
      1.1777185136470167,
      -1.4745208573506723,
      -1.699726591438122
    ],
    "value": [null, null, null, null, null, null]
  },
  "latest": {
    "raw": -3.4562255141040934,
    "value": -0.7167616272036208
  },
  "parameters": {},
  "diagnostics": {
    "causal": true,
    "input_count": 96
  }
}

Diagrams#

Calculation flow#

flowchart LR
    A["basis-consistent OHLCV observations with venue/session cov"] --> B["Validate order, basis, and finite values"]
    B --> C["Apply the selected Ease of Movement convention"]
    C --> D["Emit value, readiness, and diagnostics"]
    D --> E["Interpret descriptively; test outcomes separately"]
    B -->|invalid or insufficient| X["Withhold output with a reason"]

stateDiagram-v2
    [*] --> Waiting
    Waiting --> Ready: enough valid causal observations
    Waiting --> Rejected: malformed or unsupported input
    Ready --> Calculated: selected formula applied
    Calculated --> Interpreted: diagnostic and limitation retained
    Interpreted --> Ready: next observation arrives
    Rejected --> Waiting: corrected input and deterministic reset

How it works#

This page states the contract — how to call it correctly. The article explains the concept: why it works, and where it breaks.

Read the article →

References#

• TA-Lib function groups — see linked primary or authoritative record
• TA-Lib C/C++ API — see linked primary or authoritative record
• TA-Lib maintained source — see linked primary or authoritative record
• Evidence decision
• Level 1 evidence map

The rest of the Volume Indicators family#

• On-Balance Volume (OBV)On-balance volume: a running total that adds the bar's volume when price closed up and subtracts it when price closed down.
• Accumulation/Distribution LineWeights each bar's volume by where the close sat within that bar's range, then accumulates.
• Chaikin Money FlowMoney-flow volume summed over a lookback and divided by total volume over the same window — the accumulation/distribution idea …
• Money Flow IndexRSI computed on typical price weighted by volume — commonly described as volume-weighted RSI, and read on the same 0–100 scale.
• Volume Price TrendLike OBV, but each bar contributes volume scaled by the size of the return rather than only its sign — so a 3% move counts for …
• Force IndexPrice change multiplied by volume, then smoothed.
• Chaikin A/D OscillatorBuilds the cumulative accumulation/distribution line from the money flow multiplier and volume, then returns the difference bet…
• Session VWAP IndicatorAccumulates typical price times volume divided by cumulative volume, restarting the accumulation at every new session.
• Anchored VWAPAccumulates typical price times volume divided by cumulative volume from a chosen anchor bar onward, with no session reset.
• Negative Volume IndexTracks a cumulative index seeded at 1000 that compounds the close-to-close return only on bars whose volume fell against the pr…
• Positive Volume IndexTracks a cumulative index seeded at 1000 that compounds the close-to-close return only on bars whose volume rose against the pr…
• Klinger Volume OscillatorSigns each bar's volume force by the direction of the high-low-close sum and weights it by where the close sits in the bar rang…
• Volume OscillatorReturns the difference between a fast and a slow simple moving average of raw volume.
• Percentage Volume OscillatorExpresses the gap between a fast and a slow EMA of volume as a percentage of the slow EMA.
• Volume Rate of ChangeMeasures the percentage change in volume against the bar period positions earlier.
• Relative VolumeDivides each bar's volume by the simple moving average of volume over the preceding window, giving a multiple of normal activity.
• Money Flow Multiplier and Money Flow VolumeReturns the per-bar money flow multiplier, the close's position within the bar range mapped to minus one through one, and that …
• Volume-Weighted MACDRuns the MACD construction on volume-weighted moving averages of close instead of exponential ones, and smooths the resulting l…
• Volume Zone OscillatorSigns each bar's volume by the direction of the close change, then expresses the EMA of that signed volume as a percentage of t…
• Twiggs Money FlowAccumulates volume weighted by where the close sits inside a range extended to include the prior close, then divides the EMA of…