Selecting columns with dplyr

In the last recipe, we introduced how to use the filter and slice functions to subset and slice data by rows. In this recipe, we will present how to select particular columns from the dataset using the select function.

Getting ready

Ensure that you completed the Enhancing a data.frame with a data.table recipe to load purchase_view.tab and purchase_order.tab as both data.frame and data.table into your R environment.

You also need to make sure that you have a version of R higher than 3.1.2 installed on your operating system.

How to do it…

Perform the following steps to select columns from the dataset:

1. First, let's select the Quantity and Price columns from the dataset:

   > select.quantity.price <-  select(order.dt, Quantity, Price)
   > head(select.quantity.price, 3)
      Quantity Price
   1:        1  1069
   2:        1  1680
   3:        1   285
   

2. Alternatively, we can rule out the Price column by placing a minus sign in front:

   > select.not.price <-  select(order.dt...