04-ModifyingDataFrame.R

# load libraries

library(readr)
library(dplyr)


# load data frame

dogs <- read_csv('dogs.csv')

# inspect data frame

head(dogs)

# add average height column

dogs <- dogs %>%
   mutate(avg_height = (height_low_inches + height_high_inches)/2)
head(dogs)

# add average height, average weight and rank change columns.

dogs <- dogs %>%
  mutate(avg_height = (height_low_inches + height_high_inches)/2)

dogs <- dogs %>%
  mutate(avg_weight = (weight_low_lbs + weight_high_lbs)/2, rank_change_13_to_16 = rank_2016 - rank_2013)
head(dogs)


# Update the code in the last code block to add the columns avg_height, avg_weight, and rank_change_13_to_16 to dogs while dropping all existing columns.

dogs <- dogs %>%
   transmute(avg_height = (height_low_inches + height_high_inches)/2, avg_weight = (weight_low_lbs + weight_high_lbs)/2,
        rank_change_13_to_16 = rank_2016 - rank_2013)
head(dogs)


# check column names

original_col_names <- colnames(dogs)

# rename data frame columns

dogs <- dogs %>%
   rename(avg_height_inches = avg_height,
   avg_weight_lbs = avg_weight,
   popularity_change_13_to_16 = rank_change_13_to_16)

# check column names

new_col_names <- colnames(dogs)
new_col_names

# Add the two columns defined below to dogs while dropping all existing columns from the data frame:
# height_average_feet is the average of height_low_inches and height_high_inches divided by 12, since there are 12 inches in 1 foot.
# popularity_change_15_to_16 is the difference in rank from rank_2016 to rank_2015.

dogs <- dogs %>%
  transmute(height_average_feet = ((height_low_inches + height_high_inches)/2)/12, popularity_change_15_to_16 = rank_2016 - rank_2015)
head(dogs)


dogs <- dogs %>%
  transmute(breed = breed,
            height_average_feet = ((height_low_inches + height_high_inches)/2)/12,
            popularity_change_15_to_16 = rank_2016 - rank_2015) %>% 
  arrange(desc(popularity_change_15_to_16))
head(dogs)