Matplotlib - user enters numeric input through figure

问题

I want my figure to have a small entry window, in which the user can type a number, and the data plotted will span that many minutes. If they enter 30, they will look at a 30-minute time window, if they type 5, matplotlib picks this up, data gets trimmed, and only 5 minutes worth of data gets shown.

How can I do this? I noticed that people on SO recommend using TkAgg, is there a way to do this without it? If I do use TkAgg, can you point me to a minimal example that does this in an interactive manner, i.e. picks up new entries that the user makes?

Thank you

EDIT: This is STREAMING data, so I want to condition to be of dynamic form, such as 'give me last 15 minutes' rather than 'give me between 2:10 and 2:25'. Also, I will performing the trimming of the data manually myself, the gui doesn't have to do it. The gui only needs to read a single number and make it available to me.

ONE MORE DETAIL: Don't worry about what happens behind the curtains, I know how to take care of it. All I want to know is simply how to read a number from a text box on a figure in matplotlib.

回答1:

I don't think you can do what you want using a text box without using a 3rd party GUI program. The example below shows how a slider can be used to change the x limits of a plot using just matplotlib itself.

The example used a Slider widget to control the xlimits. You can find another example of using many widgets here.

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.widgets import Slider

# Create some random data
x = np.linspace(0,100,1000)
y = np.sin(x) * np.cos(x)

left, bottom, width, height = 0.15, 0.02, 0.7, 0.10

fig, ax = plt.subplots()

plt.subplots_adjust(left=left, bottom=0.25) # Make space for the slider

ax.plot(x,y)

# Set the starting x limits
xlims = [0, 1]
ax.set_xlim(*xlims)

# Create a plt.axes object to hold the slider
slider_ax = plt.axes([left, bottom, width, height])
# Add a slider to the plt.axes object
slider = Slider(slider_ax, 'x-limits', valmin=0.0, valmax=100.0, valinit=xlims[1])

# Define a function to run whenever the slider changes its value.
def update(val):
    xlims[1] = val
    ax.set_xlim(*xlims)

    fig.canvas.draw_idle()

# Register the function update to run when the slider changes value
slider.on_changed(update)

plt.show()

Below are some plots showing the slider at different positions: