Making a line plot in python by importing data from a csv file.

plotgraph.py

import numpy as np
import matplotlib.pyplot as plt

# importing data from csv file
xs, ys, zs = np.loadtxt("data.txt", unpack=True, delimiter=",", dtype=float)

# plotting
plt.plot(xs, ys, "b-", label="line one") # blue line, label displayed in legend
plt.plot(xs, zs, "r-", label="line two") # red line, for scatter plot replace with "ro"

# labels
plt.ylim(1, 100) # sets range for y axis
plt.xlim(1, 100) # sets range for x axis
plt.legend(loc='best', prop={'size': 10}) # size and location of plot legend
plt.xlabel("x axis label")
plt.ylabel("y axis label")
plt.title("title of figure")
plt.yticks([48, 56, 64, 72, 80, 88, 96]) # use this array to demarcate ticks on y axis

# save plot to file in current working directory
plt.savefig("fig.png") 

# display plot on screen
plt.show()