Added demonstration and exercise on using sapply() function.

RBeginnersExercise2.Rmd

@@ -91,6 +91,19 @@ The `class()` function in R can be used to find the datatype of a specific colum
 
 ```
 
+To find the datatype of all columns in a table, R supports the `sapply(list, function)` function which applies the same function to a list of items. The code below shows an example of using this function to find the datatype of all columns in the `menu` table. 
+
+```{r}
+sapply(menu, class)
+```
+
+Try to find the datatype of all columns in the  `students` table by using the `sapply()` function. 
+
+```{r}
+# Write your code below
+sapply(students, class)
+```
+
 ## 2.2.5 Summary of dataset
 
 Use the `summary()` function to get a summary of all columns in the `menu` dataset.
@@ -109,6 +122,13 @@ The `unique()` function in R can be used to find all unique values in a specific
 
 ```
 
+By using the `sapply()` function, try to find the unique values in each column in the `menu` table. 
+
+```{r}
+# Write your code below
+
+```
+
 ## 2.2.7 Incomplete cases in dataset
 
 In R, incomplete cases are rows in dataset that have `Na` value(s). These incomplete cases can be viewed using the function `complete.cases`.

RBeginnersExercise2_Sol.Rmd

@@ -91,6 +91,20 @@ The `class()` function in R can be used to find the datatype of a specific colum
 class(menu$Price)
 ```
 
+To find the datatype of all columns in a table, R supports the `sapply(list, function)` function which applies the same function to a list of items. The code below shows an example of using this function to find the datatype of all columns in the `menu` table. 
+
+```{r}
+sapply(menu, class)
+```
+
+Try to find the datatype of all columns in the  `students` table by using the `sapply()` function. 
+
+```{r}
+# Write your code below
+sapply(students, class)
+```
+
+
 ## 2.2.5 Summary of dataset
 
 Use the `summary()` function to get a summary of all columns in the `menu` dataset.
@@ -109,6 +123,14 @@ The `unique()` function in R can be used to find all unique values in a specific
 unique(menu$Price)
 ```
 
+By using the `sapply()` function, try to find the unique values in each column in the `menu` table. 
+
+```{r}
+# Write your code below
+sapply(menu, unique)
+```
+
+
 ## 2.2.7 Incomplete cases in dataset
 
 In R, incomplete cases are rows in dataset that have `Na` value(s). These incomplete cases can be viewed using the function `complete.cases`.