Question

我试图获得一个matplotlib绘图函数，以便能够生成一个x轴设置为时间轴的图形。但是，当我尝试针对UNIX时间绘制一些值时，我遇到错误ValueError: year is out of range。出了什么问题以及如何解决？

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

您需要将类似时间戳的x数据转换为python datetime对象，然后可以在matplotlib中使用，并由matplotlib.dates.DateFormatter理解。

可以使用datetime.datetime.fromtimestamp()方法完成此操作。

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()

Answer 2

虽然未直接解决问题的文本，但当人们尝试在时间轴单位与绘图数据的时间轴单位不匹配的现有轴上绘制数据时，也可能发生标题中提到的错误。

＆＃34; ValueError：年份超出范围＆＃34;当试图使用matplotlib pyplot

2 个答案: