10.51 Ordered Factor

20180723 Given our knowledge that compass directions have an obvious order, we convert the direction variables into an ordered factor. We do so using ordered=TRUE with base::factor().

# Note the names of the wind direction variables.

ds %>%
  select(contains("_dir")) %>%
  names() %T>%
  print() ->
vnames

## [1] "wind_gust_dir" "wind_dir_9am"  "wind_dir_3pm"

# Convert these variables from character to factor.

ds[vnames] %<>%
  lapply(factor, levels=compass, ordered=TRUE) %>%
  data.frame() %>%
  as_tibble()
# Confirm they are now factors.

ds[vnames] %>% sapply(class)

##      wind_gust_dir wind_dir_9am wind_dir_3pm
## [1,] "ordered"     "ordered"    "ordered"   
## [2,] "factor"      "factor"     "factor"

We can again obtain a distribution of the variables to confirm that all we have changed is the data type.

# Verify the distribution has not changed.

ds %>%
  select(contains("_dir")) %>%
  sapply(table)

##     wind_gust_dir wind_dir_9am wind_dir_3pm
## N           16541        21256        16216
## NNE         12612        15373        12754
## NE          13743        14276        15672
## ENE         15575        14991        14845
## E           17553        17767        15694
## ESE         14533        15250        16360
## SE          17929        17753        19749
## SSE         16995        17509        17123
## S           17588        16357        18466
## SSW         17296        14577        16147
## SW          16601        15771        16969
....

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