A Kagi chart is a Japanese charting technique that displays price movements using vertical lines of varying thickness. Unlike time-based charts, Kagi charts change direction only when price moves by a significant amount (the reversal threshold), effectively filtering out market noise. Thick lines (yang) indicate uptrends when price exceeds previous highs, while thin lines (yin) show downtrends when price falls below previous lows, making trend identification intuitive.
""" anyplot.ai
kagi-basic: Basic Kagi Chart
Library: plotnine 0.15.4 | Python 3.13.13
Quality: 92/100 | Updated: 2026-05-17
"""
import os
import numpy as np
import pandas as pd
from plotnine import (
aes,
element_blank,
element_line,
element_rect,
element_text,
geom_segment,
ggplot,
labs,
scale_color_manual,
scale_size_manual,
theme,
theme_minimal,
)
# Theme tokens
THEME = os.getenv("ANYPLOT_THEME", "light")
PAGE_BG = "#FAF8F1" if THEME == "light" else "#1A1A17"
ELEVATED_BG = "#FFFDF6" if THEME == "light" else "#242420"
INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
INK_SOFT = "#4A4A44" if THEME == "light" else "#B8B7B0"
RULE = "rgba(26,26,23,0.10)" if THEME == "light" else "rgba(240,239,232,0.10)"
# imprint semantic anchors (green for yang/bullish, red for yin/bearish)
YANG_COLOR = "#009E73"
YIN_COLOR = "#AE3030"
# Generate synthetic stock price data
np.random.seed(42)
n_days = 250
# Create random walk with trend
returns = np.random.normal(0.0005, 0.02, n_days)
prices = 100 * np.exp(np.cumsum(returns))
dates = pd.date_range("2024-01-01", periods=n_days, freq="B")
df_prices = pd.DataFrame({"date": dates, "close": prices})
# Kagi chart algorithm with reversal threshold
def build_kagi_data(prices, reversal_pct=0.04):
"""Build Kagi chart segments from price series."""
kagi_segments = []
if len(prices) < 2:
return pd.DataFrame()
# Initialize
direction = 1 if prices[1] > prices[0] else -1
high = prices[0]
low = prices[0]
x_idx = 0
segment_start_price = prices[0]
# Track yang/yin state (thick/thin)
is_yang = direction == 1
for i in range(1, len(prices)):
price = prices[i]
if direction == 1:
if price > high:
high = price
is_yang = True
elif price < high * (1 - reversal_pct):
kagi_segments.append(
{
"x": x_idx,
"x_end": x_idx,
"y": segment_start_price,
"y_end": high,
"trend": "yang" if is_yang else "yin",
}
)
kagi_segments.append(
{"x": x_idx, "x_end": x_idx + 1, "y": high, "y_end": high, "trend": "yang" if is_yang else "yin"}
)
x_idx += 1
direction = -1
segment_start_price = high
low = price
high = price
else:
if price < low:
low = price
is_yang = False
elif price > low * (1 + reversal_pct):
kagi_segments.append(
{
"x": x_idx,
"x_end": x_idx,
"y": segment_start_price,
"y_end": low,
"trend": "yin" if not is_yang else "yang",
}
)
kagi_segments.append(
{"x": x_idx, "x_end": x_idx + 1, "y": low, "y_end": low, "trend": "yin" if not is_yang else "yang"}
)
x_idx += 1
direction = 1
segment_start_price = low
high = price
low = price
# Add final segment
final_price = prices[-1]
final_trend = "yang" if is_yang else "yin"
if direction == 1:
kagi_segments.append(
{
"x": x_idx,
"x_end": x_idx,
"y": segment_start_price,
"y_end": max(high, final_price),
"trend": final_trend,
}
)
else:
kagi_segments.append(
{"x": x_idx, "x_end": x_idx, "y": segment_start_price, "y_end": min(low, final_price), "trend": final_trend}
)
return pd.DataFrame(kagi_segments)
# Build Kagi data with 4% reversal threshold
kagi_df = build_kagi_data(df_prices["close"].values, reversal_pct=0.04)
# Create plot with trend layers and legend
plot = (
ggplot(kagi_df, aes(x="x", xend="x_end", y="y", yend="y_end", color="trend", size="trend"))
+ geom_segment(lineend="round")
+ scale_color_manual(
values={"yang": YANG_COLOR, "yin": YIN_COLOR}, labels={"yang": "Yang (Bullish)", "yin": "Yin (Bearish)"}
)
+ scale_size_manual(values={"yang": 2, "yin": 0.7})
+ labs(x="Kagi Line Index", y="Price ($)", title="kagi-basic · plotnine · anyplot.ai", color="Trend")
+ theme_minimal()
+ theme(
figure_size=(16, 9),
plot_background=element_rect(fill=PAGE_BG, color=PAGE_BG),
panel_background=element_rect(fill=PAGE_BG),
panel_grid_major=element_line(color=INK, size=0.3, alpha=0.10),
panel_grid_minor=element_blank(),
panel_border=element_line(color=INK_SOFT),
axis_title=element_text(size=20, color=INK),
axis_text=element_text(size=16, color=INK_SOFT),
axis_line=element_line(color=INK_SOFT),
plot_title=element_text(size=24, color=INK),
legend_background=element_rect(fill=ELEVATED_BG, color=INK_SOFT),
legend_text=element_text(size=16, color=INK_SOFT),
legend_title=element_text(size=18, color=INK),
legend_position="right",
text=element_text(size=14),
)
)
# Save plot
plot.save(f"plot-{THEME}.png", dpi=300, verbose=False)
Part of Basic Kagi Chart on anyplot.ai.