For these exercises we will use the US murders dataset again. Make sure you load it prior to starting.

library(dslabs)
data("murders")

You can create a data frame using the data.frame function. Here is a quick example:

temp <- c(35, 88, 42, 84, 81, 30)
city <- c("Beijing", "Lagos", "Paris", "Rio de Janeiro", 
          "San Juan", "Toronto")
city_temps <- data.frame(name = city, temperature = temp)

Exercise

1. Use the rank function to determine the population rank of each state from smallest population size to biggest. Save these ranks in an object called ranks, then create a data frame with the state name and its rank. Call the data frame my_df and its 2 column respectively state and rank.

2. Order the dataframe my_df from smallest to largest population. Call the data frame my_df_ordered and its 2 columns respectively state and rank.

   Hint:

   create an object ind using the order function that stores the indexes of the rows sorted by their corresponding population values. Then use the bracket operator ([) to re-order the rows of the dataframe.