`BOP`#

Description#

BOP (Balance of Power, Igor Livshin) measures whether a bar closes near its high (buyers in control) or its low (sellers in control):

\[ \text{BOP}[t] = \frac{\text{close} - \text{open}}{\text{high} - \text{low}} \]

Output range is [-1, +1] for any sensibly-formed bar (where low ≤ open, close ≤ high).

4-input, 1-output (FunctorBase<_, 4, 1>). Argument order matches TA-Lib's BOP: (open, high, low, close).

Warmup: none -- stateless, value defined for every input.

Range-zero: returns 0 when high == low (flat bar; convention matches TA-Lib).

NaN handling#

Policy: ignore. A NaN in any input at index t causes the function to skip that step: output at t is NaN and internal state is unchanged. Subsequent finite samples are processed as if step t had not occurred.

Examples#

Usage example#

import numpy as np
import plotly.graph_objects as go
from plotly.subplots import make_subplots
from screamer import BOP

np.random.seed(0)
close = 100*np.exp(np.cumsum(np.random.normal(0, 0.01, size=300)))
open_ = np.concatenate([[close[0]], close[:-1]])
wick = np.abs(np.random.normal(0, 0.4, size=300))
high = np.maximum(open_, close) + wick
low  = np.minimum(open_, close) - wick
out = BOP()(open_, high, low, close)

fig = make_subplots(rows=2, cols=1, shared_xaxes=True,
                    row_heights=[0.55, 0.45], vertical_spacing=0.08)
fig.add_trace(go.Scatter(y=close, name="close", line=dict(color="royalblue")), row=1, col=1)
fig.add_trace(go.Scatter(y=out, name="BOP", line=dict(color="red")), row=2, col=1)
fig.update_layout(title="Balance of power (BOP)",
                  margin=dict(l=20, r=20, t=60, b=20),
                  legend=dict(orientation="h", yanchor="bottom", y=1.02, xanchor="right", x=1))
fig.update_yaxes(title_text="close", row=1, col=1)
fig.update_yaxes(title_text="BOP (-1 to 1)", row=2, col=1)
fig.show()

Implementation Details#

Single per-step arithmetic operation; O(1) per step, zero state.

Reference#

Bit-exact match to talib.BOP(open, high, low, close) (verified to 0.0 -- exact integer-rounded arithmetic).

BOP#