Text and Annotations#


Support for modifying text is not complete as none of the function implemented support updating fontdict or other text properties like size and color. However, the core functionality is there to place text, change it’s position, or change what it reads. see https://github.com/ianhi/mpl-interactions/issues/247 for updates.

%matplotlib ipympl
import matplotlib.pyplot as plt
import numpy as np

from mpl_interactions import ipyplot as iplt

Working with text strings.#

There are two ways to dynamically update text strings in mpl-interactions.

  1. Use a function to return a string

  2. Use a named string formatting

You can also combine these and have your function return a string that then gets formatted.

In the example below the xlabel is generated using a function and the title is generated using the formatting approach.

fig, ax = plt.subplots()

x = np.linspace(0, np.pi, 100)

def y(x, volts, tau):
    return np.sin(x * tau) * volts

ctrls = iplt.plot(x, y, volts=(0.5, 10), tau=(1, 10, 100))

def xlabel_func(tau):
    # you can do arbitrary python here to make a more
    # complicated string
    return f"Time with a max tau of {np.round(tau, 3)}"

with ctrls["tau"]:
with ctrls:
    # directly using string formatting
    # the formatting is performed in the update
    iplt.title(title="The voltage is {volts:.2f}")

Arbitrarily placed text#

For this you can use interactive_text(). Currently plt.annotation is not supported.

fig, ax = plt.subplots()

theta = np.linspace(0, 2 * np.pi, 100)

def gen_string(theta):
    return f"angle = {np.round(np.rad2deg(theta))}"

def fx(theta):
    return np.cos(theta)

def fy(x, theta):
    return np.sin(theta)

ctrls = iplt.text(fx, fy, gen_string, theta=theta)
ax.set_xlim([-1.25, 1.25])
_ = ax.set_ylim([-1.25, 1.25])

Since the x and y positions are scalars you can also do nifty things like directly define them by a slider shorthand in the function.

fig, ax = plt.subplots()
ctrls = iplt.text((0, 1, 100), (0.25, 1, 100), "{x:.2f}, {y:.2f}")