从python的txt文件中提取两列数字并绘制它们

Question

I need some very basic help with Python in PyCharm. I'm trying to extract two columns of numbers from a .txt file(But the amount of numbers in each column is something that changes ) and then plot them. So far that's my code.

pacient = str(input("Please enter your the name of the pacient: "))
Pname = pacient+'.txt'
print(Pname)
file  = open(Pname,"r")
print (file.read())

# what i need in here is save the first column of the .txt in 't' and the second one in 'v'. 



import matplotlib.pyplot as plt
plt.plot(t, v)
plt.xlabel('time (v)')
plt.ylabel('Velocity (m/s)')
plt.title(pacient+"plot")
plt.savefig("test.png")
plt.show()

Answer 1

You can use csv module to read the file:

import csv

t = []
v = []
with open(Pname, "r") as patient_f:
    csv_f = csv.reader(patient_f, delimieter='delimiter_between_columns')
    for row in csv_f:
        t.append(row[0])
        v.append(row[1])

Answer 2

what you can do is use numpy to order the columns for you:

import numpy as np
file = np.loadtxt("filename.txt", delimiter=',') #do not need delimiter if your file is not csv. 
t = file[:,0]
v = [:,1]

plt.plot(t, v)
plt.show()
plt.xlabel('time (v)')
plt.ylabel('Velocity (m/s)')
plt.title(pacient+"plot")
plt.savefig("test.png")
plt.show()

Another way without numpy:

file = open('filename.txt').readlines()
file = [map(int, i.strip('\n').split()) for i in file]
new_data = [list(i) for i in zip(*file)]

plt.plot(new_data[0], new_data[1])
plt.show()