172 lines
4.1 KiB
TeX
172 lines
4.1 KiB
TeX
\documentclass{beamer}
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\usepackage{graphicx}
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\usepackage{multicol}
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\usepackage{hyperref}
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\usepackage{verbatim}
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\usepackage{lipsum} % for placeholder text
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\graphicspath{{pdf_images/}}
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\title{ECON 4530/5530 \\ Computational Economics}
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\subtitle{Joining data and Data Transformation}
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\author{Alex Gebben}
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\begin{document}
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% Title Slide
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\begin{frame}
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\titlepage
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\end{frame}
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%%%%%%%%%%%%%%%%%%
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\begin{frame}{Joining Data}
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\begin{itemize}
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\item Real-world data often comes in multiple tables.
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\item Joins combine related data based on common keys.
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\item \texttt{dplyr} provides intuitive functions for joining.
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\end{itemize}
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\end{frame}
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% Slide 2
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\begin{frame}{Types of Joins}
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\begin{itemize}
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\item \texttt{left\_join()} – keep all rows from left table
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\item \texttt{right\_join()} – keep all rows from right table
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\item \texttt{inner\_join()} – keep only matching rows
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\item \texttt{full\_join()} – keep all rows from both tables
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\end{itemize}
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\end{frame}
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% Slide 3
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\begin{frame}{left\_join()}
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\texttt{left\_join(df1, df2, by = "id")}
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\newline
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OR
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\newline
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\onslide<2->{\texttt{df1 \%>\% left\_join(df2)}}
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\begin{itemize}
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\onslide<3->{ \item Keeps all rows from the left table.}
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\onslide<4->{ \item Adds matching rows from the right table.}
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\onslide<5->{ \item Missing matches are filled with \texttt{NA}.}
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\end{itemize}
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\end{frame}
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% Slide 4
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\begin{frame}{right\_join()}
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\texttt{right\_join(df1, df2, by = "id")}
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\newline
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OR
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\newline
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\onslide<2->{\texttt{df2 \%>\% left\_join(df1)}}
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\onslide<3->{
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\begin{itemize}
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\item Keeps all rows from the right table.
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\item Adds matching rows from the left table.
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\end{itemize}
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}
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\end{frame}
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% Slide 5
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\begin{frame}{inner\_join()}
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\texttt{inner\_join(df1, df2, by = "id")}
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\newline
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OR
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\newline
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\texttt{df1 \%>\% inner\_join(df2, by = "id")}
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\begin{itemize}
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\item Keeps only rows with matching keys in both tables.
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\item Most commonly used for filtering to shared data.
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\end{itemize}
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\end{frame}
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% Slide 6
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\begin{frame}{full\_join()}
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\texttt{full\_join(df1, df2, by = "id")}
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\newline
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OR
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\newline
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\texttt{df1 \%>\% full\_join(df2, by = "id")}
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\begin{itemize}
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\item Keeps all rows from both tables.
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\item Missing matches are filled with \texttt{NA}.
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\end{itemize}
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\end{frame}
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\begin{frame}{Common Issues}
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\begin{itemize}
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\item Mismatched column names
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\item Duplicate keys – can lead to unexpected row duplication
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\item Data types must match, both keys should be character or numeric
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\item Missing value joins will introduce \texttt{NA}s
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\end{itemize}
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\end{frame}
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\begin{frame}[plain]
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\includegraphics[width=\textwidth]{venn.png}
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\end{frame}
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\begin{frame}[plain]
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\begin{columns}
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\begin{column}{0.5\textwidth}
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\includegraphics[width=\textwidth]{1_join}
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\end{column}
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\begin{column}{0.5\textwidth}
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\includegraphics[width=\textwidth]{2_join}
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\end{column}
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\end{columns}
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\end{frame}
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\begin{frame}[plain]
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\includegraphics[width=\textwidth]{3_join}
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\end{frame}
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\begin{frame}[plain]
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\includegraphics[width=\textwidth]{full.png}
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\end{frame}
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\begin{frame}[plain]
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\includegraphics[width=\textwidth]{left.png}
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\end{frame}
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\begin{frame}[plain]
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\includegraphics[width=\textwidth]{right.png}
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\end{frame}
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% Slide 7
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\begin{frame}[plain]
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\includegraphics[width=\textwidth]{match-types.png}
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\end{frame}
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\begin{frame}{Checking with Anti-Joins}
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\includegraphics[width=\textwidth]{anti.png}
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\end{frame}
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\begin{frame}{Checking with Anti-Joins}
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\includegraphics[width=\textwidth]{anti.png}
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\end{frame}
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\begin{frame}{Filtering with semi-joins}
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\includegraphics[width=\textwidth]{semi.png}
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\end{frame}
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\begin{frame}{Other non-equa joins}
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\includegraphics[width=\textwidth]{gte}
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\end{frame}
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% Slide 8
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\begin{frame}{Best Practices}
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\begin{itemize}
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\item Inspect keys before joining: \texttt{unique()}
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\item Use \texttt{anti\_join()} to find unmatched rows
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\item Validate results with \texttt{summary()} and \texttt{count()}
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\end{itemize}
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\end{frame}
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% Slide 9
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\begin{frame}{Class Exercise}
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\begin{itemize}
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\item Joins are essential for combining data.
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\item Choose the right join based on your goal.
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\item Always check for common issues before and after joining.
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\end{itemize}
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\end{frame}
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\end{document}
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