\documentclass{beamer}
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\title{ECON 4530/5530 \\ Computational Economics}
\subtitle{Data transformation}
\author{Alex Gebben}

\begin{document}

% Title Slide
\begin{frame}
  \titlepage
\end{frame}
%%%%%%%%%%%%%%%%%%
\begin{frame}{Commenting Code}
	\only<1-3>{
	\onslide<1-3>{Comments are lines of code which do not run. These are \textbf{\emph{very}} important. }
	\newline
	\onslide<2-3>{	In R these are created by starting a line with ``\#''}
\onslide<3>{
	\begin{enumerate}
		\item{You should add a comment to any line of code which is not highly simple.}
		\item{Keep a clean comment style}
		\item{Comment above a section of code. Indent the following code}
		\item{Always include the why of your code. The what and how of your code is less critical} 
		\item{Think about what you would need to know if you forgot everything about the project}
	\end{enumerate}
}
}
\only<4>{
	  \includegraphics[width=0.7\textwidth]{What_Comments}
	  \includegraphics[width=\textwidth]{Why_Comments}

  }
\end{frame}
\begin{frame}{Section Comments}
	Section comments visually separate chunks of code. It is an excellent practice to distinguish types of analysis, or groups of code.
	\newline
\vspace{1em}
\onslide<2->{\includegraphics[width=\textwidth]{Section_comments.png}}
	\newline
\vspace{1em}
\onslide<3->{RStudio provides a keyboard shortcut to create these headers \texttt{(Cmd/Ctrl + Shift + R)}}
\end{frame}
%%%%%%%%%%%%
\begin{frame}{\emph{if} statements}
	\only<1-8>{
	\emph{If} only run code when certain condtions are met
	\newline
	\onslide<2->{	\textbf{Possible uses}}
	\begin{enumerate}
		\onslide<3->{\item Load a file only if it does not exist }
		\onslide<4->{\item Switch the value of an entry}
		\onslide<5->{\item Create a new dummy variable}
		\onslide<6->{\item Account for changes in column names on servers}
	\end{enumerate}
	\onslide<7->{Can be combined with \emph{else}}
	\newline
	\onslide<8->{The R function \texttt{ifelse()} can be a good shortcut}
}
\only<9>{\includegraphics[width=0.75\textwidth]{If.png}}
\end{frame}
%%%%%%%%%%%%%%%%
\begin{frame}{Class Exercise}
Use an if statement to write a csv file in a ``Data'' directory if the folder exists, otherwise it creates the directory first.
\end{frame}
%%%%%%%%%%%%
\begin{frame}{functions}
	\only<1-6>{
	\emph{functions} save a set of code to use later.
	\newline
	\onslide<2->{They are exactly the same as the functions you already use in R}
	\onslide<3->{Must define function inputs, code and output}
	\begin{enumerate}
		\onslide<4->{\item Use if you repeat code more than twice }
		\onslide<4->{\item Stores complex code avoids typos}
		\onslide<5->{\item Can be loaded in script files}
		\onslide<6->{\item Could be used in your own library}
	\end{enumerate}
}
\only<7>{\includegraphics[width=\textwidth]{Function.png}}
\only<8>{The \texttt{try()} function can be useful when creating your own functions. It prevents the code from stopping after a failure. Use with care.}
\end{frame}
%%%%%%%%%%%%%%%%
\begin{frame}{Class Exercise}
	Turn the previous if statement into a function. Allow the user to pass in the name of the folder that is created. 
\end{frame}
%%%%%%%%%%%%%%%%%%%
\begin{frame}{Class Exercise}
	\only<1>{\LARGE Remember proper naming of files, data and scripts. Provide clear comments.}
\only<2>{
	\begin{enumerate}
\item Identify three data set you are interested in on FRED
	\item Load one data set using a URL saved as a character variable
	\item Create a raw data subdirectory and save the raw data into it
	\item Clean the data, at least update the column names
	\item Save the cleaned data as a CSV and an RDS file in a cleaned data subdirectory with proper names
	\item Include a comment on the first line of the file explain what the code is used for and why.
	\item Comment any other code as needed
	\item Turn this code into a function where the user passes in the URL, and column names
	\item Save function in a separate Rscript in a directory for scripts. Pay attention to the name
	\item In the main directory create a Rscript and in that script load script 
	\item Use the function to clean all three data sets 
	\item After this add a section of code to find the mean, and summary of the data
\end{enumerate}
}
\end{frame}

\end{document}