matplotlib数值按乱序绘制 [英] matplotlib numeric values are plotted out of order

问题描述

我有一个数据文件，该数据文件包含多个y(y的+ ve和-ve值)，对应于一个x值，如果我尝试使用matplotlib对其进行绘制，则会出现曲折线，我什至尝试了 np.sort 函数，但是并没有帮助.我附上 2 个数字，1 个是我需要的，2 个是我使用 matplotlib 得到的.任何评论/建议都会有很大帮助.

I have a data file that consist of multiple y (+ve and -ve values of y) values corresponding to a single x value, if I am trying to plot it using the matplotlib I am getting a zig-zag line, I even tried with the np.sort function, but it hasn't helped. I am attaching 2 figures, the 1 one what I need and 2 one what I am getting using the matplotlib. Any comment/suggestion will be a great help.

import pandas as pd
import matplotlib.pyplot as plt

data = {0: [0.9991008043, 0.7186818868, 0.5990678817, 0.000260249999, -0.0002838699947, 0.9982619435, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.5990678817, 0.9987124801, 0.9983241558, 0.9979358315, 0.9975475073],
        1: [0.141599882, -0.0239639965, -0.8235306015, -0.5624349256, 0.9576566094, 0.1070839175, -0.7615373918, -0.7436025052, -0.7207683284, -0.7181828611, -0.7169656166, -0.7189734963, -0.7248864019, -0.7334572909, -0.7431326927, -0.7535460886, -0.7653977208, -0.7772543193, -0.7850276183, -0.7882964598, -0.788996217, -0.7894645357, -0.7800111345, -0.7680467609, -0.7651210906, -0.7626205455, 0.1662477571, 0.1776703065, 0.178896989, 0.1792297328]}
df = pd.DataFrame(data)

          0         1
0  0.999101  0.141600
1  0.718682 -0.023964
2  0.599068 -0.823531

plt.plot( df.iloc[:,0], df.iloc[:,1], marker="o", linewidth=2)

推荐答案

• 在这种情况下，数据被正确地转换为数字(例如 float)，但使用 df 验证列 dtypes 通常是个好主意.info()
• 需要使用 pandas.DataFrame.sort_values() 对 x 轴值进行排序
  • 我通常也会重置索引，但这并不是绝对必要的.
  • In this case, the data is correctly cast as numeric (e.g. float), but it's usually a good idea to verify the column dtypes with df.info()
  • It's required to sort the x-axis values with pandas.DataFrame.sort_values()
    • I typically also reset the index, but it's not strictly necessary.

    # sort the values for the x-axis, which is column 0
    df = df.sort_values(0).reset_index(drop=True)
    
    # plot the sorted data
    plt.plot(df.iloc[:,0], df.iloc[:,1], marker="o", linewidth=2)
    

    • 也可以使用 pandas.DataFrame.plot
    绘制数据

    df.plot(x=0, y=1, marker='o', legend=False)
    

    这篇关于matplotlib数值按乱序绘制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！