Array 的 Python Plot 产生两行而不是一行

Question

Plotted an array generated from comma separated files and it plotted two lines instead of the correct one (orange). If any one has could offer a solution or any suggestions it would be greatly appreciated!

import numpy as np
import matplotlib.pyplot as plt
file = open("com.txt","r")
X, Y = [], []
npy_array = np.loadtxt(file, delimiter=",")
plt.plot(npy_array)
plt.show()

enter image description here

Answer 1

It seems that you have loaded tabulated data into a 2d array. You need to separate this into independent and dependent variables and then plot one against the other, rather than plot both lines against the array index. (Clearly the linearly increasing data in your blue line is intended to be the independent variable, and should be your "x" values, ranging from 0 to approximately 0.2.) Assuming that the lines of the file are in the order x,y, you would do this -- otherwise swap the 0 and 1.

# to start with, some lines unchanged from the question
import numpy as np
import matplotlib.pyplot as plt
file = open("com.txt","r")
npy_array = np.loadtxt(file, delimiter=",")

# below here: what you need to change
x = npy_array[:,0]
y = npy_array[:,1]
plt.plot(x, y)

Answer 2

matplotlib plots 2d numpy arrays assuming each column is a different set of data, and should each be plotted indigently

a = [[0,1,2,3], [0,2,3,6]]
np_a = np.array(a)
plt.plot(np_a,'x:')
plt.show()

because the line is a strait one, I assume you want that to be your x axis. To do that you have to pass the x axis as the first perimeter, and the y axis as the second

a = [[0,1,2,3], [0,2,3,6]]
np_a = np.array(a)
plt.plot(np_a[0],np_a[1],'x:')
plt.show()