An OHLC (Open-High-Low-Close) bar chart displays financial price data using vertical bars with horizontal tick marks. Each bar shows the price range from high to low as a thin vertical line, with a left tick indicating the opening price and a right tick indicating the closing price. Unlike candlestick charts that use colored bodies, OHLC bars provide a cleaner, less cluttered view favored by technical analysts who prefer to focus on price levels rather than visual patterns.
""" anyplot.ai
ohlc-bar: OHLC Bar Chart
Library: matplotlib 3.10.9 | Python 3.13.13
Quality: 91/100 | Updated: 2026-05-17
"""
import os
import matplotlib.dates as mdates
import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
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"
# imprint semantic anchors
COLOR_UP = "#009E73" # green — up bars
COLOR_DOWN = "#AE3030" # red — down bars
# Data - Generate 45 trading days of synthetic stock OHLC data
np.random.seed(42)
n_days = 45
# Start from a base price and simulate random walk with some trend
base_price = 150.0
dates = pd.bdate_range(start="2024-06-01", periods=n_days)
# Generate price movements
returns = np.random.normal(0.001, 0.02, n_days) # Daily returns with slight upward bias
cumulative_returns = np.cumprod(1 + returns)
close_prices = base_price * cumulative_returns
# Generate OHLC data with realistic intraday ranges
high_add = np.random.uniform(0.5, 3.0, n_days)
low_sub = np.random.uniform(0.5, 3.0, n_days)
# Open is close of previous day (with small gap)
open_prices = np.roll(close_prices, 1) * (1 + np.random.uniform(-0.005, 0.005, n_days))
open_prices[0] = base_price
# High and low must encompass open and close
high_prices = np.maximum(open_prices, close_prices) + high_add
low_prices = np.minimum(open_prices, close_prices) - low_sub
# Create DataFrame
df = pd.DataFrame({"date": dates, "open": open_prices, "high": high_prices, "low": low_prices, "close": close_prices})
# Plot
fig, ax = plt.subplots(figsize=(16, 9), facecolor=PAGE_BG)
ax.set_facecolor(PAGE_BG)
# Draw OHLC bars
tick_width = 0.4 # Width of open/close ticks in days
line_width = 2.0
for _idx, row in df.iterrows():
date_num = mdates.date2num(row["date"])
# Determine color based on price direction
color = COLOR_UP if row["close"] >= row["open"] else COLOR_DOWN
# Draw high-low vertical line
ax.plot([date_num, date_num], [row["low"], row["high"]], color=color, linewidth=line_width, solid_capstyle="round")
# Draw open tick (left side)
ax.plot(
[date_num - tick_width, date_num],
[row["open"], row["open"]],
color=color,
linewidth=line_width,
solid_capstyle="butt",
)
# Draw close tick (right side)
ax.plot(
[date_num, date_num + tick_width],
[row["close"], row["close"]],
color=color,
linewidth=line_width,
solid_capstyle="butt",
)
# Style
ax.set_xlabel("Date", fontsize=20, color=INK)
ax.set_ylabel("Price (USD)", fontsize=20, color=INK)
ax.set_title("ohlc-bar · matplotlib · anyplot.ai", fontsize=24, fontweight="medium", color=INK)
ax.tick_params(axis="both", labelsize=16, colors=INK_SOFT)
# Format x-axis dates
ax.xaxis.set_major_locator(mdates.WeekdayLocator(byweekday=mdates.MONDAY))
ax.xaxis.set_major_formatter(mdates.DateFormatter("%b %d"))
ax.xaxis.set_minor_locator(mdates.DayLocator())
fig.autofmt_xdate(rotation=45)
# Spine styling
for spine in ("top", "right"):
ax.spines[spine].set_visible(False)
for spine in ("left", "bottom"):
ax.spines[spine].set_color(INK_SOFT)
# Grid for reading price levels
ax.yaxis.grid(True, alpha=0.15, linewidth=0.8, color=INK)
ax.xaxis.grid(True, alpha=0.08, linewidth=0.8, color=INK)
# Add padding to y-axis
y_min, y_max = ax.get_ylim()
y_padding = (y_max - y_min) * 0.05
ax.set_ylim(y_min - y_padding, y_max + y_padding)
# Add legend for up/down bars
legend_elements = [
Line2D([0], [0], color=COLOR_UP, linewidth=3, label="Up (Close ≥ Open)"),
Line2D([0], [0], color=COLOR_DOWN, linewidth=3, label="Down (Close < Open)"),
]
legend = ax.legend(handles=legend_elements, fontsize=16, loc="upper left")
legend.get_frame().set_facecolor(ELEVATED_BG)
legend.get_frame().set_edgecolor(INK_SOFT)
for text in legend.get_texts():
text.set_color(INK_SOFT)
plt.tight_layout()
plt.savefig(f"plot-{THEME}.png", dpi=300, bbox_inches="tight", facecolor=PAGE_BG)
Runnable source as JSON, for any HTTP client: https://api.anyplot.ai/specs/ohlc-bar/matplotlib/code. Any spec id and library id listed in llms-full.txt fit the same URL shape; every URL below is complete and callable.
{
"spec_id": "ohlc-bar",
"language": "python",
"library": "matplotlib",
"page": "https://anyplot.ai/ohlc-bar/python/matplotlib",
"hub": "https://anyplot.ai/ohlc-bar",
"code_json": "https://api.anyplot.ai/specs/ohlc-bar/matplotlib/code",
"spec_json": "https://api.anyplot.ai/specs/ohlc-bar",
"render_light_png": "https://storage.googleapis.com/anyplot-images/plots/ohlc-bar/python/matplotlib/plot-light.png",
"render_dark_png": "https://storage.googleapis.com/anyplot-images/plots/ohlc-bar/python/matplotlib/plot-dark.png",
"quality_score": 91.0,
"license": "MIT",
"guide": "https://anyplot.ai/llms.txt"
}Part of OHLC Bar Chart on anyplot.ai.