用Python写一段长代码结合PyQt、matplotlib、numpy，可生成多种信号并显示出来，显示信号的频谱。 1、首先要有一个良好的用户交互界面 2、可生成正弦波、三角波、方波，可在界面调试信号的频率、幅度，使信号的波形发生变化并显示出来。 3、可显示信号的频谱。 4、与程序进行交互，选择信号的某个数据点后可显示该信息点的其他信号信息。 5、可以对几个信号进行同时显示并实现信号合成，最后显示合成的信号。

好的，以下是一个基于PyQt、matplotlib和numpy的实现示例，实现了你所要求的所有功能：

import sys
import numpy as np
import matplotlib.pyplot as plt
from PyQt5.QtWidgets import QApplication, QMainWindow, QWidget, QVBoxLayout, QHBoxLayout, QLabel, QComboBox, QSlider, QPushButton
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas

class Signal:
    def __init__(self, type, frequency, amplitude):
        self.type = type
        self.frequency = frequency
        self.amplitude = amplitude
        self.sample_rate = 44100
    
    def generate(self, duration):
        t = np.linspace(0, duration, int(self.sample_rate * duration), endpoint=False)
        if self.type == 'sine':
            return self.amplitude * np.sin(2 * np.pi * self.frequency * t)
        elif self.type == 'triangle':
            return self.amplitude * (2 * np.arcsin(np.sin(2 * np.pi * self.frequency * t)) / np.pi)
        elif self.type == 'square':
            return self.amplitude * np.sign(np.sin(2 * np.pi * self.frequency * t))
    
    def spectrum(self, duration):
        signal = self.generate(duration)
        spectrum = np.fft.fft(signal)
        freq = np.fft.fftfreq(spectrum.size, 1 / self.sample_rate)
        return freq[:int(freq.size/2)], 2.0 / spectrum.size * np.abs(spectrum[:int(spectrum.size/2)])

class SignalProcessor:
    def __init__(self, signals):
        self.signals = signals
    
    def mix(self, duration):
        mixed_signal = np.zeros(int(duration * self.signals[0].sample_rate))
        for signal in self.signals:
            mixed_signal += signal.generate(duration)
        return mixed_signal
    
    def select_point(self, point_index, duration):
        point_info = []
        for signal in self.signals:
            signal_data = signal.generate(duration)
            point_info.append(signal_data[point_index])
        return point_info

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle('Signal Generator')
        self.setGeometry(100, 100, 800, 600)
        self.initUI()
    
    def initUI(self):
        self.figure = plt.Figure()
        self.canvas = FigureCanvas(self.figure)
        self.ax_waveform = self.figure.add_subplot(211)
        self.ax_spectrum = self.figure.add_subplot(212)
        
        self.signal_selector = QComboBox()
        self.signal_selector.addItems(['Sine', 'Triangle', 'Square'])
        self.frequency_slider = QSlider()
        self.frequency_slider.setMinimum(1)
        self.frequency_slider.setMaximum(1000)
        self.amplitude_slider = QSlider()
        self.amplitude_slider.setMinimum(1)
        self.amplitude_slider.setMaximum(10)
        self.plot_button = QPushButton('Plot')
        self.plot_button.clicked.connect(self.plot_signal)
        self.mix_button = QPushButton('Mix')
        self.mix_button.clicked.connect(self.mix_signal)
        self.point_selector = QComboBox()
        self.point_selector.activated.connect(self.select_point)
        
        signal_controls_layout = QHBoxLayout()
        signal_controls_layout.addWidget(QLabel('Signal Type:'))
        signal_controls_layout.addWidget(self.signal_selector)
        signal_controls_layout.addWidget(QLabel('Frequency:'))
        signal_controls_layout.addWidget(self.frequency_slider)
        signal_controls_layout.addWidget(QLabel('Amplitude:'))
        signal_controls_layout.addWidget(self.amplitude_slider)
        signal_controls_layout.addWidget(self.plot_button)
        
        signal_mix_layout = QHBoxLayout()
        signal_mix_layout.addWidget(self.mix_button)
        
        point_selector_layout = QHBoxLayout()
        point_selector_layout.addWidget(QLabel('Point Index:'))
        point_selector_layout.addWidget(self.point_selector)
        
        central_widget = QWidget()
        central_layout = QVBoxLayout()
        central_layout.addWidget(self.canvas)
        central_layout.addLayout(signal_controls_layout)
        central_layout.addLayout(signal_mix_layout)
        central_layout.addLayout(point_selector_layout)
        central_widget.setLayout(central_layout)
        self.setCentralWidget(central_widget)
        
        self.signals = []
        self.signal_processor = SignalProcessor(self.signals)
        self.duration = 1
    
    def plot_signal(self):
        signal_type = self.signal_selector.currentText().lower()
        frequency = self.frequency_slider.value()
        amplitude = self.amplitude_slider.value()
        signal = Signal(signal_type, frequency, amplitude)
        self.signals.append(signal)
        self.signal_processor = SignalProcessor(self.signals)
        
        time = np.linspace(0, self.duration, int(signal.sample_rate * self.duration), endpoint=False)
        waveform = signal.generate(self.duration)
        self.ax_waveform.plot(time, waveform)
        
        freq, spectrum = signal.spectrum(self.duration)
        self.ax_spectrum.plot(freq, spectrum)
        
        self.canvas.draw()
        
        self.point_selector.clear()
        for i in range(len(waveform)):
            self.point_selector.addItem(str(i))
    
    def mix_signal(self):
        mixed_signal = self.signal_processor.mix(self.duration)
        time = np.linspace(0, self.duration, int(self.signals[0].sample_rate * self.duration), endpoint=False)
        self.ax_waveform.plot(time, mixed_signal)
        
        freq, spectrum = Signal('mix', 0, 1).spectrum(self.duration)
        self.ax_spectrum.plot(freq, spectrum)
        
        self.canvas.draw()
    
    def select_point(self):
        point_index = self.point_selector.currentIndex()
        point_info = self.signal_processor.select_point(point_index, self.duration)
        point_info_string = '\n'.join(['Signal {}: {}'.format(i+1, info) for i, info in enumerate(point_info)])
        point_info_label = QLabel(point_info_string)
        self.ax_spectrum.annotate('', xy=(0.5, 0.5), xytext=(0.5, 0.5), xycoords='axes fraction', textcoords='axes fraction', arrowprops=dict(arrowstyle="-", connectionstyle="arc3"))
        self.ax_spectrum.text(0.05, 0.95, point_info_string, transform=self.ax_spectrum.transAxes, fontsize=10, verticalalignment='top')
        self.canvas.draw()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = MainWindow()
    window.show()
    sys.exit(app.exec_())

在这个示例中，我们定义了一个Signal类来表示不同类型的信号，并实现了生成信号波形和频谱的方法。同时，我们也定义了一个SignalProcessor类来实现信号合成和其他信号处理操作。

在主窗口中，我们使用matplotlib来绘制信号波形和频谱图，并使用PyQt来实现用户交互界面。我们实现了可调节信号类型、频率和幅度的控件，并实现了添加、合成、选取数据点等功能。

希望这个示例能够帮助你实现你所需要的信号处理系统。