Matplotlib y 轴值未排序 [英] Matplotlib y axis values are not ordered

问题描述

我正在尝试使用 matplotlib 进行绘图.该图显示了 Y 轴未排序的问题.

I am trying to plot using matplotlib. The plot showed a problem that the Y axis is not ordered.

这是代码.

# -*- coding: UTF-8 -*-
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
import datetime
import numpy as np
I020 = [ line.strip('
').split(",") for line in 
open(r'D:Usersa0476Anaconda3TickDataPV5sdata1.csv')][1:]
Time = [ datetime.datetime.strptime(line[0],"%H%M%S%f") for line in I020 ]
Time1 = [ mdates.date2num(line) for line in Time ]
Solar = [ line[1] for line in I020 ]
order = np.argsort(Time1)
xs = np.array(Time1)[order]
ys = np.array(Solar)[order]
plt.title('Solar data')
plt.xlabel('Time')
plt.ylabel('Solar')
ax.plot_date(xs, ys, 'k-')
hfmt = mdates.DateFormatter('%H:%M:%S')
ax.xaxis.set_major_formatter(hfmt)
plt.show()

CSV 数据

time        solar
7000000     50.35
8000000     41.01
9000000     69.16
10000000    94.5
11000000    111.9
12000000    103
13000000    98.6
14000000    36.45
15000000    34.74
16000000    34.17
17000000    34.6

推荐答案

发生这种情况的原因是您的数据被绘制为字符串.

The reason this happens is because your data is being plotted as strings.

解决方案是将 y 轴数据转换为浮点数.这可以通过简单地转换为列表理解中的浮点数来完成:

The solution is to convert your y axis data to floats. This can be done by simply casting to a float in your list comprehension:

Solar = [float(line[1]) for line in I020]

我还建议在使用日期/时间时使用 matplotlib 的 x 轴自动格式化.这将旋转标签等以使图表看起来更好:

I would also suggest to use matplotlib's auto formatting of the x -axis when using dates/times. This will rotate the labels etc to make the graph look better:

plt.gcf().autofmt_xdate()

你的例子变成:

I020 = [ line.strip('
').split(",") for line in open('PV5sdata1.csv')][1:]
Time = [datetime.datetime.strptime(line[0],"%H%M%S%f") for line in I020]
Time1 = [mdates.date2num(line) for line in Time]
Solar = [float(line[1]) for line in I020]

xs = np.array(Time1)  # You don't really need to do this but I've left it in
ys = np.array(Solar)

fig, ax = plt.subplots() # using matplotlib's Object Oriented API

ax.set_title('Solar data')
ax.set_xlabel('Time')
ax.set_ylabel('Solar')
ax.plot_date(xs, ys, 'k-')

hfmt = mdates.DateFormatter('%H:%M:%S')
ax.xaxis.set_major_formatter(hfmt)
plt.gcf().autofmt_xdate()

plt.show()

给出:

这篇关于Matplotlib y 轴值未排序的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！