import numpy as np v0 = [] v1 = [] v2 = [] for k in range(0,1000): with open("output/part-%05d" % k) as f : for l in f : w = l.split(" ") if w[0] == "P" : u = float(w[4]) print(u) v0.append(u) v0 = np.array(v0) from matplotlib import pyplot as plt plt.plot(v0) plt.show()