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: matplotlib 3.10.9 | Python 3.13.13
Quality: 90/100 | Updated: 2026-05-17
"""
import os
import matplotlib.pyplot as plt
import numpy as np
from matplotlib.lines import Line2D
# 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"
INK_MUTED = "#6B6A63" if THEME == "light" else "#A8A79F"
# Data colors (Okabe-Ito palette, theme-independent)
COLOR_YANG = "#009E73" # imprint green — bullish
COLOR_YIN = "#AE3030" # imprint red — bearish
# Generate synthetic stock price data
np.random.seed(42)
n_days = 250
initial_price = 100.0
# Create realistic price movements using geometric brownian motion
daily_returns = np.random.normal(0.0003, 0.015, n_days)
prices = initial_price * np.cumprod(1 + daily_returns)
# Kagi chart construction
reversal_pct = 0.04 # 4% reversal threshold
# Initialize Kagi data structures
kagi_x = [0]
kagi_y = [prices[0]]
kagi_colors = []
kagi_widths = []
current_direction = None # 'up' or 'down'
current_price = prices[0]
last_high = prices[0]
last_low = prices[0]
is_yang = True # Start as yang (thick line)
x_pos = 0
for price in prices[1:]:
reversal_amount = current_price * reversal_pct
if current_direction is None:
# Initialize direction based on first significant move
if price >= current_price + reversal_amount:
current_direction = "up"
is_yang = True
kagi_x.append(x_pos)
kagi_y.append(price)
kagi_colors.append(COLOR_YANG)
kagi_widths.append(4)
current_price = price
last_high = price
elif price <= current_price - reversal_amount:
current_direction = "down"
is_yang = False
kagi_x.append(x_pos)
kagi_y.append(price)
kagi_colors.append(COLOR_YIN)
kagi_widths.append(2)
current_price = price
last_low = price
elif current_direction == "up":
if price > current_price:
# Continue upward - extend line
kagi_y[-1] = price
current_price = price
# Check if we broke previous high -> become yang
if price > last_high:
is_yang = True
kagi_colors[-1] = COLOR_YANG
kagi_widths[-1] = 4
last_high = price
elif price <= current_price - reversal_amount:
# Reversal down - draw horizontal then vertical
x_pos += 1
# Horizontal shoulder line
kagi_x.append(x_pos)
kagi_y.append(current_price)
kagi_colors.append(COLOR_YANG if is_yang else COLOR_YIN)
kagi_widths.append(4 if is_yang else 2)
# New vertical down line
kagi_x.append(x_pos)
kagi_y.append(price)
# Check if we broke previous low -> become yin
if price < last_low:
is_yang = False
last_low = price
kagi_colors.append(COLOR_YANG if is_yang else COLOR_YIN)
kagi_widths.append(4 if is_yang else 2)
current_direction = "down"
current_price = price
elif current_direction == "down":
if price < current_price:
# Continue downward - extend line
kagi_y[-1] = price
current_price = price
# Check if we broke previous low -> become yin
if price < last_low:
is_yang = False
kagi_colors[-1] = COLOR_YIN
kagi_widths[-1] = 2
last_low = price
elif price >= current_price + reversal_amount:
# Reversal up - draw horizontal then vertical
x_pos += 1
# Horizontal waist line
kagi_x.append(x_pos)
kagi_y.append(current_price)
kagi_colors.append(COLOR_YANG if is_yang else COLOR_YIN)
kagi_widths.append(4 if is_yang else 2)
# New vertical up line
kagi_x.append(x_pos)
kagi_y.append(price)
# Check if we broke previous high -> become yang
if price > last_high:
is_yang = True
last_high = price
kagi_colors.append(COLOR_YANG if is_yang else COLOR_YIN)
kagi_widths.append(4 if is_yang else 2)
current_direction = "up"
current_price = price
# Plot
fig, ax = plt.subplots(figsize=(16, 9), facecolor=PAGE_BG)
ax.set_facecolor(PAGE_BG)
# Draw Kagi lines segment by segment
for i in range(len(kagi_colors)):
ax.plot(
[kagi_x[i], kagi_x[i + 1]],
[kagi_y[i], kagi_y[i + 1]],
color=kagi_colors[i],
linewidth=kagi_widths[i],
solid_capstyle="round",
)
# Style
ax.set_xlabel("Kagi Line Index", fontsize=20, color=INK)
ax.set_ylabel("Price ($)", fontsize=20, color=INK)
ax.set_title("kagi-basic · matplotlib · anyplot.ai", fontsize=24, fontweight="medium", color=INK)
ax.tick_params(axis="both", labelsize=16, colors=INK_SOFT)
for s in ("left", "bottom"):
ax.spines[s].set_color(INK_SOFT)
ax.spines["top"].set_visible(False)
ax.spines["right"].set_visible(False)
ax.yaxis.grid(True, alpha=0.10, linewidth=0.8, color=INK)
# Legend
legend_elements = [
Line2D([0], [0], color=COLOR_YANG, linewidth=4, label="Yang (Bullish)"),
Line2D([0], [0], color=COLOR_YIN, linewidth=2, label="Yin (Bearish)"),
]
leg = ax.legend(handles=legend_elements, fontsize=16, loc="upper left")
if leg:
leg.get_frame().set_facecolor(ELEVATED_BG)
leg.get_frame().set_edgecolor(INK_SOFT)
plt.setp(leg.get_texts(), color=INK_SOFT)
# Annotation explaining reversal threshold
ax.text(
0.98,
0.02,
f"Reversal threshold: {reversal_pct * 100:.0f}%",
transform=ax.transAxes,
fontsize=14,
ha="right",
va="bottom",
color=INK,
bbox={"boxstyle": "round", "facecolor": ELEVATED_BG, "edgecolor": INK_SOFT, "alpha": 0.9},
)
plt.tight_layout()
plt.savefig(f"plot-{THEME}.png", dpi=300, bbox_inches="tight", facecolor=PAGE_BG)
Part of Basic Kagi Chart on anyplot.ai.