create-chart

name	create-chart
description	Create interactive Our World In Data style charts using the owid-grapher-py Python library. Use this skill when the user wants to visualize data as charts (line charts, bar charts, scatter plots, maps, etc.) in a Jupyter notebook, standalone HTML, or export charts to PNG/SVG.
allowed-tools	["Bash(uv:*)","Bash(python:*)","Bash(curl:*)","Bash(open:*)","WebFetch","Write","Read"]
metadata	{"internal":true}

The owid-grapher-py library creates interactive charts that look and behave like Our World In Data charts. Charts render in Jupyter notebooks and can be exported to PNG, SVG, or standalone HTML.

Installation

uv pip install owid-grapher-py

For PNG/SVG export, install Playwright and its browser as two separate steps:

uv pip install playwright
playwright install chromium

IMPORTANT: Before Writing Code

The library is under active development. Always fetch the latest documentation first:

curl -sL "https://raw.githubusercontent.com/owid/owid-grapher-py/master/llms-full.txt"

This provides comprehensive API documentation including all functions, parameters, and examples. Do not rely on cached knowledge about this library.

Quick Start: Standalone Script (No Jupyter)

For quick visualizations without Jupyter, create a Python script with inline uv dependencies:

# /// script
# requires-python = ">=3.10"
# dependencies = [
#     "owid-grapher-py",
#     "pandas",
#     "requests",
# ]
# ///

import io
import pandas as pd
import requests
from owid.grapher import plot

# Fetch data from an OWID chart URL
url = "https://ourworldindata.org/grapher/life-expectancy"
resp = requests.get(f"{url}.csv?useColumnShortNames=true", headers={"User-Agent": "owid-grapher-py"})
resp.raise_for_status()
df = pd.read_csv(io.StringIO(resp.text))
df = df.rename(columns={"Entity": "entity", "Year": "year"})

# Always print columns — names aren't predictable from the URL
print(f"Columns: {list(df.columns)}")

# Create chart — plot() is the simplest way
chart = plot(
    df,
    y="life_expectancy",
    title="Life Expectancy",
    types=["line", "map"],
    entities=["France", "Brazil", "Japan"],
)

# Save and display
html = chart.to_html()
with open("chart.html", "w") as f:
    f.write(html)
print("Chart saved to chart.html")

Run with:

uv run --no-project script.py && open chart.html

The --no-project flag ensures uv uses an isolated environment with only the script's inline dependencies.

Loading OWID Data

Do NOT use pd.read_csv(url) directly — it will get a 403 error. You need a User-Agent header:

import io, pandas as pd, requests

url = "https://ourworldindata.org/grapher/annual-co2-emissions-per-country"
resp = requests.get(f"{url}.csv?useColumnShortNames=true", headers={"User-Agent": "owid-grapher-py"})
resp.raise_for_status()
df = pd.read_csv(io.StringIO(resp.text))
df = df.rename(columns={"Entity": "entity", "Year": "year"})

Always print columns after loading — the value column names are not predictable from the chart URL (e.g. the chart annual-co2-emissions-per-country has a column called emissions_total, not annual_co2).

Data Requirements

The DataFrame must have:

• entity column: Groups data into separate lines/series (e.g., country names)
• year column: Time dimension for the x-axis
• value column(s): Numeric data to plot

Creating Charts

Use plot() by default — it handles most cases in a single call:

from owid.grapher import plot
plot(df, y="value", title="My Chart", entities=["France", "Japan"], types=["line", "map"])

plot() accepts chart type, entity selection, color scheme, units, and more as parameters. See llms-full.txt for the full signature.

Use Chart() when you need finer control (e.g. multiple mark types with different options, axis configuration, transforms):

Exporting to PNG / SVG

Requires Playwright (see installation above). Use save_png() or save_svg() on the chart object returned by plot():

chart = plot(df, y="value", title="My Chart", types=["map", "line"])

chart.save_png("chart.png")
chart.save_svg("chart.svg")

Important: The exported image renders the first tab in types=[]. So if you want a map PNG, put "map" first: types=["map", "line"]. For a line chart PNG, use types=["line", "map"].