A Renko chart displays price movements using fixed-size bricks that ignore time and focus purely on price action. A new brick is drawn only when the price moves by a specified amount (brick size), filtering out market noise and minor fluctuations. Bullish bricks (price increase) and bearish bricks (price decrease) alternate direction on trend reversals, making it easy to identify trends, support/resistance levels, and potential trading signals.
""" anyplot.ai
renko-basic: Basic Renko Chart
Library: plotnine 0.15.4 | Python 3.13.13
Quality: 85/100 | Updated: 2026-05-17
"""
import os
import sys
import numpy as np
import pandas as pd
# Work around naming collision with plotnine.py
sys.path.pop(0)
from plotnine import (
aes,
element_line,
element_rect,
element_text,
geom_rect,
ggplot,
labs,
scale_fill_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"
# imprint semantic anchors for direction
BULLISH = "#009E73" # green - up bricks
BEARISH = "#AE3030" # red - down bricks
# Data - Generate stock price data
np.random.seed(42)
n_days = 250
dates = pd.date_range("2024-01-01", periods=n_days, freq="D")
returns = np.random.normal(0.0005, 0.018, n_days)
prices = 100 * np.cumprod(1 + returns)
price_data = pd.DataFrame({"date": dates, "close": prices})
# Renko brick calculation
brick_size = 2.0 # $2 brick size
bricks = []
current_price = price_data["close"].iloc[0]
brick_start = (current_price // brick_size) * brick_size
direction = None # None initially, then 'up' or 'down'
for close_price in price_data["close"]:
while True:
if direction is None:
# First brick - determine initial direction
if close_price >= brick_start + brick_size:
bricks.append(
{
"brick_num": len(bricks),
"bottom": brick_start,
"top": brick_start + brick_size,
"direction": "up",
}
)
brick_start += brick_size
direction = "up"
elif close_price <= brick_start - brick_size:
bricks.append(
{
"brick_num": len(bricks),
"bottom": brick_start - brick_size,
"top": brick_start,
"direction": "down",
}
)
brick_start -= brick_size
direction = "down"
else:
break
elif direction == "up":
if close_price >= brick_start + brick_size:
bricks.append(
{
"brick_num": len(bricks),
"bottom": brick_start,
"top": brick_start + brick_size,
"direction": "up",
}
)
brick_start += brick_size
elif close_price <= brick_start - 2 * brick_size:
# Reversal requires 2x brick size
brick_start -= brick_size
bricks.append(
{
"brick_num": len(bricks),
"bottom": brick_start - brick_size,
"top": brick_start,
"direction": "down",
}
)
brick_start -= brick_size
direction = "down"
else:
break
else: # direction == 'down'
if close_price <= brick_start - brick_size:
bricks.append(
{
"brick_num": len(bricks),
"bottom": brick_start - brick_size,
"top": brick_start,
"direction": "down",
}
)
brick_start -= brick_size
elif close_price >= brick_start + 2 * brick_size:
# Reversal requires 2x brick size
brick_start += brick_size
bricks.append(
{
"brick_num": len(bricks),
"bottom": brick_start,
"top": brick_start + brick_size,
"direction": "up",
}
)
brick_start += brick_size
direction = "up"
else:
break
brick_df = pd.DataFrame(bricks)
# Create rectangle coordinates for geom_rect
brick_df["xmin"] = brick_df["brick_num"] + 0.1
brick_df["xmax"] = brick_df["brick_num"] + 0.9
brick_df["ymin"] = brick_df["bottom"]
brick_df["ymax"] = brick_df["top"]
# Plot
plot = (
ggplot(brick_df, aes(xmin="xmin", xmax="xmax", ymin="ymin", ymax="ymax", fill="direction"))
+ geom_rect(color=INK_SOFT, size=0.3)
+ scale_fill_manual(values={"up": BULLISH, "down": BEARISH}, labels={"up": "Bullish", "down": "Bearish"})
+ labs(x="Brick Index", y="Price ($)", title="renko-basic · plotnine · anyplot.ai", fill="Direction")
+ theme_minimal()
+ theme(
figure_size=(16, 9),
text=element_text(size=14, color=INK),
axis_title=element_text(size=20, color=INK),
axis_text=element_text(size=16, color=INK_SOFT),
plot_title=element_text(size=24, color=INK),
legend_text=element_text(size=16, color=INK_SOFT),
legend_title=element_text(size=18, color=INK),
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=0.5, alpha=0.15),
panel_grid_minor=element_line(color=INK, size=0.3, alpha=0.08),
panel_border=element_rect(color=INK_SOFT, fill=None, size=0.3),
legend_background=element_rect(fill=ELEVATED_BG, color=INK_SOFT),
axis_line=element_line(color=INK_SOFT, size=0.3),
)
)
plot.save(f"plot-{THEME}.png", dpi=300, width=16, height=9)
Part of Basic Renko Chart on anyplot.ai.