add loc and iloc to subsetting (#23812)

broaden subetting topic to include the other slicing/indexing methods

guide/english/data-science-tools/pandas/index.md

@@ -45,11 +45,16 @@ df.tail()
 ```
 This will show the last 5 rows of the data frame.
 
-## Subsetting: Getting a column by name
+## Subsetting
 A data frame can be subset in many ways. One of the simplest is getting a single column. For instance, if the data frame `df` contains a column named `age`, we can extract it as follows:
 ```python
 ages=df["age"]
 ```
+Another option for subsetting a dataframe is using the loc and iloc methods. The difference between loc and iloc is that loc searches based on a label and iloc searches based on the integer value of a row or column. To perform the same indexing as the above example using loc:
+```python
+ages=df.loc["age"]
+```
+
 
 #### More Information:
 1. [pandas](http://pandas.pydata.org/)