Reading and Writing Data

A short description of the post.

1.Load the R packages we will use.

  1. Download \(CO_2\) emission per capita from Our World in Data into the directory for this post.

  2. Assign the location of the file to ‘file_CSV’. the data should be in the same directory as this file.

file_CSV  <- here("_posts",
                  "2021-03-02-reading-and-writing-data",
                  "co-emissions-per-capita.csv")

emissions  <- read_csv(file_CSV)

4.Show the first 10 rows (observation of) ‘emissions’

emissions  
# A tibble: 22,383 x 4
   Entity      Code   Year `Per capita CO2 emissions`
   <chr>       <chr> <dbl>                      <dbl>
 1 Afghanistan AFG    1949                    0.00191
 2 Afghanistan AFG    1950                    0.0109 
 3 Afghanistan AFG    1951                    0.0117 
 4 Afghanistan AFG    1952                    0.0115 
 5 Afghanistan AFG    1953                    0.0132 
 6 Afghanistan AFG    1954                    0.0130 
 7 Afghanistan AFG    1955                    0.0186 
 8 Afghanistan AFG    1956                    0.0218 
 9 Afghanistan AFG    1957                    0.0343 
10 Afghanistan AFG    1958                    0.0380 
# ... with 22,373 more rows
  1. Start with ‘emissions’ data. THEN use ‘clean_names’ from the janitor package to make the names easier to work with assign the output to ‘tidy_emissions’
tidy_emissions   <- emissions %>%
  clean_names()

tidy_emissions
# A tibble: 22,383 x 4
   entity      code   year per_capita_co2_emissions
   <chr>       <chr> <dbl>                    <dbl>
 1 Afghanistan AFG    1949                  0.00191
 2 Afghanistan AFG    1950                  0.0109 
 3 Afghanistan AFG    1951                  0.0117 
 4 Afghanistan AFG    1952                  0.0115 
 5 Afghanistan AFG    1953                  0.0132 
 6 Afghanistan AFG    1954                  0.0130 
 7 Afghanistan AFG    1955                  0.0186 
 8 Afghanistan AFG    1956                  0.0218 
 9 Afghanistan AFG    1957                  0.0343 
10 Afghanistan AFG    1958                  0.0380 
# ... with 22,373 more rows
  1. Start with the ‘tidy_emissions’. THEN use ‘filter’ to extract rows with ‘year == 1984’. THEN use ‘skim’ to calculate the descriptive statistics.
tidy_emissions  %>%
  filter(year == 1984) %>%
  skim()
Table 1: Data summary
Name Piped data
Number of rows 209
Number of columns 4
_______________________
Column type frequency:
character 2
numeric 2
________________________
Group variables None

Variable type: character

skim_variable n_missing complete_rate min max empty n_unique whitespace
entity 0 1.00 4 32 0 209 0
code 12 0.94 3 8 0 197 0

Variable type: numeric

skim_variable n_missing complete_rate mean sd p0 p25 p50 p75 p100 hist
year 0 1 1984.00 0.0 1984.00 1984.00 1984.0 1984.00 1984.0 ▁▁▇▁▁
per_capita_co2_emissions 0 1 5.31 8.3 0.04 0.51 2.4 7.55 75.6 ▇▁▁▁▁
  1. 13 observations have a missing code. How are these observations different? Start with ‘tidy_emissions’. then extract rows with ‘year == 1984’ and are missing a code.
tidy_emissions  %>%
  filter(year == 1984, is.na(code))
# A tibble: 12 x 4
   entity                     code   year per_capita_co2_emissions
   <chr>                      <chr> <dbl>                    <dbl>
 1 Africa                     <NA>   1984                     1.23
 2 Asia                       <NA>   1984                     1.74
 3 Asia (excl. China & India) <NA>   1984                     2.71
 4 EU-27                      <NA>   1984                     9.08
 5 EU-28                      <NA>   1984                     9.11
 6 Europe                     <NA>   1984                    10.5 
 7 Europe (excl. EU-27)       <NA>   1984                    12.5 
 8 Europe (excl. EU-28)       <NA>   1984                    13.2 
 9 North America              <NA>   1984                    13.3 
10 North America (excl. USA)  <NA>   1984                     5.04
11 Oceania                    <NA>   1984                    10.7 
12 South America              <NA>   1984                     1.87
  1. Start with ’tidy_emissions. Then
emissions_1984  <- tidy_emissions  %>% 
  filter(year == 1984, !is.na(code))   %>% 
  select(-year)  %>% 
  rename(country = entity)
  1. which 15 countries have the highest ‘per_capita_co2-emissions’?
max_15_emitters  <- emissions_1984  %>%
  slice_max(per_capita_co2_emissions, n = 15)
  1. which 15 countries have the lowest ‘per_capita_co2-emissions’?
min_15_emitters  <- emissions_1984  %>%
  slice_min(per_capita_co2_emissions, n = 15)
  1. Use ‘bind_rows’ to bind together the ‘max_15_emitters’ and ‘min_15_emitters’
max_min_15  <- bind_rows(max_15_emitters, min_15_emitters)
  1. Export ’max_min_15 to 3 file formats
max_min_15  %>% write_csv("max_min_15.csv")# comma-separated values
max_min_15  %>% write_tsv("max_min_15.tsv")  # tab separated
max_min_15  %>% write_delim("max_min_15.psv", delim = "|" ) # pipe separated
  1. Read the 3 file formats into R
max_min_15_csv <-  read_csv("max_min_15.csv") # comma-separated values
max_min_15_tsv <-  read_tsv("max_min_15.tsv")  # tab separated
max_min_15_psv <-  read_delim("max_min_15.psv", delim = "|" ) # pipe separated
  1. Use ‘setdiff’ to chack for any differences among ‘max_min_15_csv’, ‘max_min_15_tsv’ and ‘max_min_15_psv’
setdiff(max_min_15_csv, max_min_15_tsv, max_min_15_psv)
# A tibble: 0 x 3
# ... with 3 variables: country <chr>, code <chr>,
#   per_capita_co2_emissions <dbl>

Are there any differences?

  1. Reorder ‘country in ’max_min_15’ for plotting and assign to max_min_15_plot_data
max_min_15_plot_data  <- max_min_15 %>%
  mutate(country = reorder(country, per_capita_co2_emissions))
  1. Plot’ max_min_15_plot_data
ggplot(data = max_min_15_plot_data, 
       mapping = aes(x= per_capita_co2_emissions, y = country)) +
  geom_col() +
  labs(title = "The top 15 and bottom 15 per capita CO2 emissions",
       subtitle = "for 1984",
       x = NULL,
       y = NULL)

  1. Save the plot directory with this post.
ggsave(filename = "preview.png", 
       path = here("_posts", "2021-03-02-reading-and-writing-data"))
  1. Add Picture to the top of file.

preview: preview.png