\documentclass[12pt]{article}

%\title{Plotting Data}

%\author{FOSSEE}

\begin{document}

\date{}

\vspace{-1in}

\begin{center}

\LARGE{Plotting Data}\\

\large{FOSSEE}

\end{center}

\section{Plotting from Data files}

\begin{verbatim}

l = [] #Empty List

t = []

for line in open('pendulum.txt'): # Opening & Reading files

    points = line.split() # Splitting a string

    l.append(float(points[0])) # Appending to a list

    t.append(float(points[1]))

tsq = []

for time in t:  #Iterating through lists

    tsq.append(t*t)

plot(l, tsq, '.') # Plotting points

\end{verbatim}

\end{document}