\documentclass{beamer}
\usepackage{graphicx}
\usepackage{multicol}
\usepackage{hyperref}
\usepackage{verbatim}
\usepackage{lipsum} % for placeholder text
\graphicspath{{pdf_images/}}


\title{ECON 4530/5530 \\ Computational Economics}
\subtitle{Joining data and Data Transformation}
\author{Alex Gebben}

\begin{document}

% Title Slide
\begin{frame}
  \titlepage
\end{frame}
%%%%%%%%%%%%%%%%%%
\begin{frame}{Joining Data}
\begin{itemize}
  \item Real-world data often comes in multiple tables.
  \item Joins combine related data based on common keys.
  \item \texttt{dplyr} provides intuitive functions for joining.
\end{itemize}
\end{frame}

% Slide 2
\begin{frame}{Types of Joins}
\begin{itemize}
  \item \texttt{left\_join()} – keep all rows from left table
  \item \texttt{right\_join()} – keep all rows from right table
  \item \texttt{inner\_join()} – keep only matching rows
  \item \texttt{full\_join()} – keep all rows from both tables
\end{itemize}
\end{frame}

% Slide 3
\begin{frame}{left\_join()}
\texttt{left\_join(df1, df2, by = "id")}
\newline
OR
\newline
\onslide<2->{\texttt{df1 \%>\% left\_join(df2)}}
\begin{itemize}
	\onslide<3->{ \item Keeps all rows from the left table.}
	\onslide<4->{ \item Adds matching rows from the right table.}
	\onslide<5->{ \item Missing matches are filled with \texttt{NA}.}
\end{itemize}
\end{frame}

% Slide 4
\begin{frame}{right\_join()}

\texttt{right\_join(df1, df2, by = "id")}
\newline
OR
\newline
\onslide<2->{\texttt{df2 \%>\% left\_join(df1)}}
\onslide<3->{
\begin{itemize}
  \item Keeps all rows from the right table.
  \item Adds matching rows from the left table.
\end{itemize}
}
\end{frame}

% Slide 5
\begin{frame}{inner\_join()}
\texttt{inner\_join(df1, df2, by = "id")}
\newline
OR
\newline
\texttt{df1 \%>\% inner\_join(df2, by = "id")}
\begin{itemize}
  \item Keeps only rows with matching keys in both tables.
  \item Most commonly used for filtering to shared data.
\end{itemize}
\end{frame}

% Slide 6
\begin{frame}{full\_join()}
\texttt{full\_join(df1, df2, by = "id")}
\newline
OR
\newline
\texttt{df1 \%>\% full\_join(df2, by = "id")}

\begin{itemize}
  \item Keeps all rows from both tables.
  \item Missing matches are filled with \texttt{NA}.
\end{itemize}
\end{frame}
\begin{frame}{Common Issues}
\begin{itemize}
  \item Mismatched column names 
  \item Duplicate keys – can lead to unexpected row duplication
  \item Data types must match, both keys should be character or numeric
  \item Missing value joins will introduce \texttt{NA}s
\end{itemize}

\end{frame}

\begin{frame}[plain]
		\includegraphics[width=\textwidth]{venn.png}
\end{frame}

\begin{frame}[plain]
	\begin{columns}
		\begin{column}{0.5\textwidth}
		\includegraphics[width=\textwidth]{1_join}
		\end{column}
		\begin{column}{0.5\textwidth}
		\includegraphics[width=\textwidth]{2_join}
		\end{column}
	\end{columns}
\end{frame}

\begin{frame}[plain]
		\includegraphics[width=\textwidth]{3_join}
\end{frame}
\begin{frame}[plain]
		\includegraphics[width=\textwidth]{full.png}
\end{frame}
\begin{frame}[plain]
		\includegraphics[width=\textwidth]{left.png}
\end{frame}
\begin{frame}[plain]
		\includegraphics[width=\textwidth]{right.png}
\end{frame}

% Slide 7
\begin{frame}[plain]
		\includegraphics[width=\textwidth]{match-types.png}
\end{frame}
\begin{frame}{Checking with Anti-Joins}
		\includegraphics[width=\textwidth]{anti.png}
\end{frame}
\begin{frame}{Checking with Anti-Joins}
		\includegraphics[width=\textwidth]{anti.png}
\end{frame}
\begin{frame}{Filtering with semi-joins}
		\includegraphics[width=\textwidth]{semi.png}
\end{frame}
\begin{frame}{Other non-equa joins}
		\includegraphics[width=\textwidth]{gte}
\end{frame}

% Slide 8
\begin{frame}{Best Practices}
\begin{itemize}
  \item Inspect keys before joining: \texttt{unique()}
  \item Use \texttt{anti\_join()} to find unmatched rows
  \item Validate results with \texttt{summary()} and \texttt{count()}
\end{itemize}
\end{frame}

% Slide 9
\begin{frame}{Class Exercise}
\begin{itemize}
  \item Joins are essential for combining data.
  \item Choose the right join based on your goal.
  \item Always check for common issues before and after joining.
\end{itemize}
\end{frame}

\begin{frame}{Pivot}
	\centering
		\includegraphics[width=0.6\textwidth]{Pivot_Data.png}
\end{frame}
\begin{frame}{Pivot longer}
	\centering
		\includegraphics[width=\textwidth]{pivot_longer.png}
\end{frame}
\begin{frame}{Pivot longer}
	\centering
		\includegraphics[width=\textwidth]{column-names.png}
\end{frame}
\begin{frame}{Pivot longer}
	\centering
		\includegraphics[width=\textwidth]{cell-values.png}
\end{frame}

\end{document}