add video for loading spreadsheets into a DataFrame

Author: Steve Baskauf

script/codegraf/ees3/index.md

@@ -180,9 +180,47 @@ states_df.loc['PA', 'population']
 
 The resulting object has the type of the cell value.
 
-
 ---
 
+# Loading a DataFrame from a file
+
+One nice thing about loading spreadsheet data into a pandas DataFrame is that the file can come either from your local file directory or from a URL. The same function can be used for either data source.
+
+## Loading a spreadsheet via a URL (3m02s)
+
+Functions for reading and writing from spreadsheets to pandas DataFrames:
+
+`pd.read_csv()` read from a CSV file into a data frame.
+
+`pd.to_csv()` write from a data frame to a CSV file.
+
+`pd.read_excel()` read from an Excel file into a data frame.
+
+`pd.to_excel()` write from a data frame to an Excel file.
+
+For details about reading from particular sheets in an Excel file, delimiters other than commas, etc. see the [pandas User Guide](https://pandas.pydata.org/docs/user_guide/io.html) and [this Stack Overflow post](https://stackoverflow.com/questions/26521266/using-pandas-to-pd-read-excel-for-multiple-worksheets-of-the-same-workbook).
+
+<iframe width="1120" height="630" src="https://www.youtube.com/embed/JVwKj7H8QU0" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
+
+Note: when loading files via a URL, be sure that the URL delivers the raw file, not an HTML representation of the file.
+
+**Examining the DataFrame**
+
+Use the `.head()` method to view only the first few lines of a DataFrame (default is 5 if `number_of_lines` argument omitted):
+```
+dataframe.head(number_of_lines)
+```
+
+The `.tail()` method is similar, but shows the last few lines of a DataFrame
+
+The `.shape` attribute returns a tuple of the number of rows and number of columns. 
+
+The `.columns` attribute returns the column names as a pandas Index object. Use the `list()` function to convert into a simple Python list.
+
+The `.index` returns the row label indices as a pandas Index object. Use the `list()` function to convert into a simple Python list.
+
+----
+
 # Loops
 
 ## for loops (5m46s)