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Money Flow Index (mfi)

[[mfi]] (Money Flow Index) combines changes in source with traded volume over a window of length values. Each candle contributes a money flow equal to source × volume. The flow is classified as positive when source rises from its previous value and negative when it falls.

The block accumulates the two categories separately and compares them to produce the MFI series. As long as source stays positive and the result is defined, MFI follows its conventional 0 to 100 scale: high values mean positive flow dominates, low values mean negative flow dominates, and values near the midpoint mean the two flows are similar in magnitude.

Block declaration

A strategy can contain multiple [[mfi]] blocks. Each block outputs one numeric series: the MFI value.

Examples

Minimal setup

[[mfi]]
id     = "mfi"
source = "hlc3"
length = 14

Specifying symbol and timeframe

This block computes MFI on daily candles for BINANCE:BTCUSDT.

[[mfi]]
id        = "mfi"
source    = "hlc3"
length    = 14
symbol    = "BINANCE:BTCUSDT"
timeframe = "D"

Finding the optimal length

This block explores a range of values for length to identify the best-performing length.

[[mfi]]
id           = "mfi"
source       = "hlc3"
length.start = 10
length.stop  = 30
length.step  = 2

Parameters

ParameterDescription
id
 String
 Required		Unique name for the MFI series.
source
 String
 or Array
 Optional		Input series used for the calculation.
Accepted forms: source = "hl2" or source = ["close", "hl2"].
Each value can be either a standard price source (open, close, high, low, hl2, hlc3, ohlc4, hlcc4, volume) or the id of another indicator.
Default value: "hlc3"
length
 Integer
 Required		Window length; must be ≥ 1.

Usage:
• Fixed: length = value
• Grid search:
 – length.start = min_value
 – length.stop = max_value
 – length.step = value (optional, default 1)
symbol
 String or Array
 Optional		Market symbol(s) used when source only consists of standard prices (open, close, high, low, hl2, hlc3, ohlc4, hlcc4, volume).
If source mixes standard prices and indicator ids, symbol is applied only to combinations based on standard prices.
If source contains only indicator ids, symbol is ignored.
If omitted, the block inherits the [backtest] symbol.
For symbol format, arrays, and alignment rules, see Exchanges, Symbols and Timeframes.
timeframe
 String or Array
 Optional		Timeframe on which this indicator is computed.
If timeframe is omitted, the computation uses the grid’s main timeframe defined in [backtest].
For accepted formats and timeframe alignment rules, see Exchanges, Symbols and Timeframes.

Available variables

Use the identifiers below directly in your expressions. The MFI block exposes its numeric series and input metadata.

Assume the block is configured as:

[[mfi]]
id     = "mfi"
source = "hlc3"
length = 14

Then:

VariableDescription
mfi or mfi[0]
Decimal		Current MFI value.
mfi[n]
Decimal		MFI value from n candles ago.
mfi.length
Decimal		Window length in use.
mfi.source
String		Input series name.
mfi.volume_source
String		Name of the volume series used.
mfi.symbol
String		Symbol used.
mfi.timeframe
String		Timeframe used.

Notes

  • If cumulative negative flow over the window is zero, the MFI value is unavailable (NaN).
  • If source changes sign, individual flow contributions can change sign as well, and the output may move outside the conventional 0 to 100 range.
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