Question

我正在尝试使用Matplotlib绘制一些测量数据。使用下面显示的代码，我得到了绘图窗口和gui，但没有绘制绘图。如果我将绘图类型改为圆形或十字形，它就可以正常工作。

# coding=utf-8
import matplotlib.pyplot as plt
import csv

with open("AgPVP8.2.171g1L#2.csv") as csvfile:
    reader = csv.reader(csvfile, delimiter=",")

    frequencies = []
    phases = []

    for row in reader:
        frequency = float(row[0])
        phase = float(row[4])

        frequencies.append(frequency)
        phases.append(phase)

plt.plot([frequencies], [phases], "b-")
plt.xscale("log")
plt.show()

Answer 1

问题是频率和阶段仅存在于with open(...的范围内，您必须将其置于此范围内：

import matplotlib.pyplot as plt
import csv

with open("AgPVP8.2.171g1L#2.csv") as csvfile:
    reader = csv.reader(csvfile, delimiter=",")

    frequencies = []
    phases = []

    for row in reader:
        frequency = float(row[0])
        phase = float(row[4])

        frequencies.append(frequency)
        phases.append(phase)
    plt.plot(frequencies, phases, "-b")
    plt.xscale("log")
    plt.show()

Answer 2

plt.plot(x,y)要求x和y为列表（或一般序列）或数组。在这里，您试图绘制列表列表，即[x]与x不同。因此，在您的代码中，您需要将plt.plot([frequencies], [phases], "b-")替换为

plt.plot(frequencies, phases, "-b")

完整的代码应如下所示：

import matplotlib.pyplot as plt
import csv

with open("AgPVP8.2.171g1L#2.csv") as csvfile:
    reader = csv.reader(csvfile, delimiter=",")

    frequencies = []
    phases = []

    for row in reader:
        frequency = float(row[0])
        phase = float(row[4])

        frequencies.append(frequency)
        phases.append(phase)

plt.plot(frequencies, phases, "b-")
plt.xscale("log")
plt.show()

我建议您查看numpy.loadtxt或numpy.genfromtxt。两者都可以在csv文件中更容易阅读，例如在这种情况下

import matplotlib.pyplot as plt
import numpy as np

frequencies, phases = np.loadtxt("AgPVP8.2.171g1L#2.csv", unpack=True, usecols = (0,4), delimiter=",")

plt.plot(frequencies, phases, "b-")
plt.xscale("log")
plt.show()

Matplotlib没有绘制线图;十字架，圆圈和三角形的工作

2 个答案: