A Gantt chart is a horizontal bar chart that visualizes project schedules and timelines. Each task is represented as a horizontal bar spanning from its start date to end date, making it easy to see task durations, overlaps, and the overall project timeline at a glance. Gantt charts are essential for project management, helping teams understand task sequences and identify scheduling conflicts.
""" anyplot.ai
gantt-basic: Basic Gantt Chart
Library: letsplot 4.9.0 | Python 3.13.13
Quality: 90/100 | Updated: 2026-05-10
"""
import os
from datetime import datetime
import pandas as pd
from lets_plot import *
LetsPlot.setup_html()
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 = ["#009E73", "#C475FD", "#4467A3", "#BD8233", "#AE3030", "#2ABCCD"]
# Data - Software Development Project
tasks_data = {
"task": [
"Requirements Gathering",
"System Design",
"UI/UX Design",
"Backend Development",
"Frontend Development",
"Database Setup",
"API Integration",
"Unit Testing",
"Integration Testing",
"User Acceptance Testing",
"Documentation",
"Deployment",
],
"category": [
"Planning",
"Planning",
"Design",
"Development",
"Development",
"Development",
"Development",
"Testing",
"Testing",
"Testing",
"Documentation",
"Deployment",
],
"start": [
datetime(2025, 1, 6),
datetime(2025, 1, 13),
datetime(2025, 1, 20),
datetime(2025, 1, 27),
datetime(2025, 2, 3),
datetime(2025, 1, 27),
datetime(2025, 2, 17),
datetime(2025, 2, 10),
datetime(2025, 2, 24),
datetime(2025, 3, 3),
datetime(2025, 2, 17),
datetime(2025, 3, 10),
],
"end": [
datetime(2025, 1, 10),
datetime(2025, 1, 17),
datetime(2025, 1, 31),
datetime(2025, 2, 14),
datetime(2025, 2, 21),
datetime(2025, 2, 7),
datetime(2025, 2, 28),
datetime(2025, 2, 21),
datetime(2025, 3, 7),
datetime(2025, 3, 14),
datetime(2025, 3, 7),
datetime(2025, 3, 14),
],
}
df = pd.DataFrame(tasks_data)
# Convert dates to numeric for plotting (days since project start)
project_start = datetime(2025, 1, 6)
project_today = datetime(2025, 2, 17)
df["start_days"] = [(d - project_start).days for d in df["start"]]
df["end_days"] = [(d - project_start).days for d in df["end"]]
df["duration"] = df["end_days"] - df["start_days"]
# Map categories to colors (Okabe-Ito palette)
category_colors = {
"Planning": IMPRINT[0],
"Design": IMPRINT[1],
"Development": IMPRINT[2],
"Testing": IMPRINT[3],
"Documentation": IMPRINT[4],
"Deployment": IMPRINT[5],
}
df["color"] = df["category"].map(category_colors)
# Order tasks by start date and assign y positions
df = df.sort_values("start_days", ascending=False).reset_index(drop=True)
df["y_pos"] = range(len(df))
# Create the Gantt chart using horizontal bars (geom_segment)
plot = (
ggplot(df, aes(x="start_days", y="y_pos"))
+ geom_segment(aes(xend="end_days", yend="y_pos", color="category"), size=12, alpha=0.85)
+ geom_point(aes(color="category"), size=4, shape=15) # Start markers
+ geom_point(aes(x="end_days", color="category"), size=4, shape=15) # End markers
+ geom_vline(xintercept=(project_today - project_start).days, color=INK_SOFT, size=1.5, linetype="dashed")
+ scale_y_continuous(breaks=list(df["y_pos"]), labels=list(df["task"]), expand=[0.05, 0.05])
+ scale_x_continuous(
name="Project Timeline (Days from Start)",
breaks=[0, 7, 14, 21, 28, 35, 42, 49, 56, 63, 70],
labels=[
"Week 1",
"Week 2",
"Week 3",
"Week 4",
"Week 5",
"Week 6",
"Week 7",
"Week 8",
"Week 9",
"Week 10",
"Week 11",
],
)
+ scale_color_manual(values=IMPRINT, name="Phase")
+ labs(title="gantt-basic · letsplot · anyplot.ai", x="Project Timeline", y="Tasks")
+ theme_minimal()
+ theme(
plot_background=element_rect(fill=PAGE_BG, color=PAGE_BG),
panel_background=element_rect(fill=PAGE_BG),
plot_title=element_text(size=28, color=INK),
axis_title_x=element_text(size=22, color=INK),
axis_title_y=element_text(size=22, color=INK),
axis_text_x=element_text(size=16, color=INK_SOFT, angle=45),
axis_text_y=element_text(size=16, color=INK_SOFT),
axis_line=element_line(color=INK_SOFT),
legend_background=element_rect(fill=ELEVATED_BG, color=INK_SOFT),
legend_title=element_text(size=18, color=INK),
legend_text=element_text(size=16, color=INK_SOFT),
legend_position="right",
panel_grid_major_x=element_line(color=RULE, size=0.3),
panel_grid_major_y=element_line(color=RULE, size=0.2),
panel_grid_minor=element_blank(),
)
+ ggsize(1600, 900)
)
# Save as PNG (scale 3x for 4800 × 2700 px)
ggsave(plot, f"plot-{THEME}.png", scale=3, path=".")
# Save interactive HTML version
ggsave(plot, f"plot-{THEME}.html", path=".")
Part of Basic Gantt Chart on anyplot.ai.