當試圖使用matplotlib pyplot時，「ValueError：year超出範圍」

Question

我正在嘗試獲取matplotlib繪圖函數，以便能夠生成一個x軸設置爲時間軸的圖形。但是，當我試圖根據UNIX時間繪製某些值時，我遇到錯誤ValueError: year is out of range。出了什麼問題，如何解決？

import os 
import time 

import matplotlib.dates 
import matplotlib.pyplot 
import shijian 

def main(): 

    data = [ 
     [1484611200.0, 844.4333], 
     [1484524800.0, 783.3373], 
     [1484438400.0, 774.194 ], 
     [1484352000.0, 769.2299] 
    ] 

    save_graph_matplotlib(
     values  = data, 
     line   = True, 
     line_width = 0.5, 
     title_axis_x = "time", 
     title_axis_y = "value", 
     #time_axis_x = True 
    ) 

def save_graph_matplotlib(
    values    = None, 
    title    = None, 
    title_axis_x  = None, 
    title_axis_y  = None, 
    filename   = None, 
    directory   = ".", 
    overwrite   = True, 
    color    = "black", 
    LaTeX    = False, 
    markers    = True, 
    marker_size   = 1, 
    aspect    = None, 
    line    = False, 
    line_style   = "-", 
    line_width   = 0.2, 
    font_size   = 20, 
    scientific_notation = False, 
    time_axis_x   = False 
    ): 

    # 1D or 2D data 
    if isinstance(values[0], list): 
     x = [element[0] for element in values] 
     y = [element[1] for element in values] 
    else: 
     x = range(0, len(values)) 
     y = values 

    matplotlib.pyplot.ioff() 
    if LaTeX is True: 
     matplotlib.pyplot.rc("text", usetex = True) 
     matplotlib.pyplot.rc("font", family = "serif") 
    if filename is None: 
     if title is None: 
      filename = "graph.png" 
     else: 
      filename = shijian.propose_filename(
       filename = title + ".png", 
       overwrite = overwrite 
      ) 
    else: 
     filename = shijian.propose_filename(
      filename = filename, 
      overwrite = overwrite 
     ) 

    figure = matplotlib.pyplot.figure() 

    if title is not None: 
     figure.suptitle(
      title, 
      fontsize = font_size 
     ) 
    if markers is True: 
     matplotlib.pyplot.scatter(
      x, 
      y, 
      s   = marker_size, 
      c   = color, 
      edgecolors = "none", 
     ) 
    if line is True: 
     matplotlib.pyplot.plot(
      x, 
      y, 
      line_style, 
      c   = color, 
      linewidth = line_width 
     ) 

    # Turn on or off axes scientific notation. 
    if scientific_notation is False: 
     matplotlib.pyplot.gca().get_xaxis().\ 
      get_major_formatter().set_scientific(False) 
     matplotlib.pyplot.gca().get_yaxis().\ 
      get_major_formatter().set_scientific(False) 
    # Set axes titles. 
    if title_axis_x is not None: 
     matplotlib.pyplot.xlabel(title_axis_x, fontsize = font_size) 
    if title_axis_y is not None: 
     matplotlib.pyplot.ylabel(title_axis_y, fontsize = font_size) 
    # Set axes font size. 
    matplotlib.pyplot.xticks(fontsize = font_size) 
    matplotlib.pyplot.yticks(fontsize = font_size) 
    # Set or do not set axis x as time. 
    if time_axis_x: 
     time_formatter = matplotlib.dates.DateFormatter("%Y-%m-%d") 
     matplotlib.pyplot.axes().xaxis_date() 
     matplotlib.pyplot.axes().xaxis.set_major_formatter(time_formatter) 
     matplotlib.pyplot.xticks(rotation = -90) 
    # Set the aspect ratio. 
    if aspect is None: 
     matplotlib.pyplot.axes().set_aspect(
      1/matplotlib.pyplot.axes().get_data_ratio() 
     ) 
    else: 
     matplotlib.pyplot.axes().set_aspect(aspect) 

    if not os.path.exists(directory): 
     os.makedirs(directory) 

    matplotlib.pyplot.savefig(
     directory + "/" + filename, 
     dpi = 700 
    ) 
    matplotlib.pyplot.close() 

if __name__ == "__main__": 
    main() 

Answer 1

您需要將時間戳樣X數據轉換爲蟒蛇DateTime對象，然後可以在matplotlib使用，由matplotlib.dates.DateFormatter理解。

這可以使用datetime.datetime.fromtimestamp()方法完成。

import datetime 
import matplotlib.dates 
import matplotlib.pyplot as plt 

data = [ 
     [1484611200.0, 844.4333], 
     [1484524800.0, 783.3373], 
     [1484438400.0, 774.194 ], 
     [1484352000.0, 769.2299] 
    ] 

x = [datetime.datetime.fromtimestamp(element[0]) for element in data] 
y = [element[1] for element in data] 

plt.plot(x, y, ls="-", c= "b", linewidth = 2) 
plt.xlabel("Dates") 

time_formatter = matplotlib.dates.DateFormatter("%Y-%m-%d") 
plt.axes().xaxis.set_major_formatter(time_formatter) 
plt.axes().xaxis_date() # this is not actually necessary 

plt.show()