knitr::opts_chunk$set(echo = TRUE)
library(tidyverse)
## ── Attaching core tidyverse packages ──────────────────────── tidyverse 2.0.0 ──
## ✔ dplyr 1.1.3 ✔ readr 2.1.4
## ✔ forcats 1.0.0 ✔ stringr 1.5.0
## ✔ ggplot2 3.4.3 ✔ tibble 3.2.1
## ✔ lubridate 1.9.2 ✔ tidyr 1.3.0
## ✔ purrr 1.0.2
## ── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
## ✖ dplyr::filter() masks stats::filter()
## ✖ dplyr::lag() masks stats::lag()
## ℹ Use the conflicted package (<http://conflicted.r-lib.org/>) to force all conflicts to become errors
library(nycflights13)
library(lubridate)
Chapter 15
Introduction
Creating Factors
General Social Survey
gss_cat
## # A tibble: 21,483 × 9
## year marital age race rincome partyid relig denom tvhours
## <int> <fct> <int> <fct> <fct> <fct> <fct> <fct> <int>
## 1 2000 Never married 26 White $8000 to 9999 Ind,near … Prot… Sout… 12
## 2 2000 Divorced 48 White $8000 to 9999 Not str r… Prot… Bapt… NA
## 3 2000 Widowed 67 White Not applicable Independe… Prot… No d… 2
## 4 2000 Never married 39 White Not applicable Ind,near … Orth… Not … 4
## 5 2000 Divorced 25 White Not applicable Not str d… None Not … 1
## 6 2000 Married 25 White $20000 - 24999 Strong de… Prot… Sout… NA
## 7 2000 Never married 36 White $25000 or more Not str r… Chri… Not … 3
## 8 2000 Divorced 44 White $7000 to 7999 Ind,near … Prot… Luth… NA
## 9 2000 Married 44 White $25000 or more Not str d… Prot… Other 0
## 10 2000 Married 47 White $25000 or more Strong re… Prot… Sout… 3
## # ℹ 21,473 more rows
Unordered Factor Levels ## Modifying factor Order
# Transform data: Calculate average tv hours by religion
tvhours_by_relig <- gss_cat %>%
group_by(relig) %>%
summarise(
avg_tvhours = mean(tvhours, na.rm = TRUE
))
tvhours_by_relig
## # A tibble: 15 × 2
## relig avg_tvhours
## <fct> <dbl>
## 1 No answer 2.72
## 2 Don't know 4.62
## 3 Inter-nondenominational 2.87
## 4 Native american 3.46
## 5 Christian 2.79
## 6 Orthodox-christian 2.42
## 7 Moslem/islam 2.44
## 8 Other eastern 1.67
## 9 Hinduism 1.89
## 10 Buddhism 2.38
## 11 Other 2.73
## 12 None 2.71
## 13 Jewish 2.52
## 14 Catholic 2.96
## 15 Protestant 3.15
# Plot
tvhours_by_relig %>%
ggplot(aes(x = avg_tvhours, y = relig)) +
geom_point()

Ordered Factor Levels
tvhours_by_relig %>%
ggplot(aes(x = avg_tvhours, y = fct_reorder(.f = relig, .x = avg_tvhours))) +
geom_point() +
# Labeling
labs(y = NULL, x = "Mean Daily Hours Watching TV")

Moving a single level to the front
tvhours_by_relig %>%
ggplot(aes(x = avg_tvhours,
y = fct_reorder(.f = relig, .x = avg_tvhours) %>%
fct_relevel("Don't know"))) +
geom_point() +
labs(y = NULL, x = "Mean Daily Hours Watching TV")

Modifying Factor Levels
gss_cat %>% distinct(race)
## # A tibble: 3 × 1
## race
## <fct>
## 1 White
## 2 Black
## 3 Other
# Recode
gss_cat %>%
# Rename levels
mutate(race_rev = fct_recode(race, "African American" = "Black")) %>%
select(race, race_rev) %>%
filter(race == "Black")
## # A tibble: 3,129 × 2
## race race_rev
## <fct> <fct>
## 1 Black African American
## 2 Black African American
## 3 Black African American
## 4 Black African American
## 5 Black African American
## 6 Black African American
## 7 Black African American
## 8 Black African American
## 9 Black African American
## 10 Black African American
## # ℹ 3,119 more rows
# Collapse multiple levels into one
gss_cat %>%
mutate(race_col = fct_collapse(race, "Minority" = c("Black", "Other"))) %>%
select(race, race_col) %>%
filter(race != "White")
## # A tibble: 5,088 × 2
## race race_col
## <fct> <fct>
## 1 Black Minority
## 2 Black Minority
## 3 Black Minority
## 4 Other Minority
## 5 Black Minority
## 6 Other Minority
## 7 Black Minority
## 8 Other Minority
## 9 Black Minority
## 10 Black Minority
## # ℹ 5,078 more rows
# Lump small levels into other levels
gss_cat %>% mutate(race_lump = fct_lump(race)) %>% distinct(race_lump)
## # A tibble: 2 × 1
## race_lump
## <fct>
## 1 White
## 2 Other
Chapter 16
Introduction
Creating date/times
From Strings
# From strings
"20222/10/28" %>% ymd()
## Warning: All formats failed to parse. No formats found.
## [1] NA
# From numbers
20221028 %>% ymd()
## [1] "2022-10-28"
"2022-10-28 4-41-30" %>% ymd_hms()
## [1] "2022-10-28 04:41:30 UTC"
From individual Components
flights %>%
select(year:day, hour, minute) %>%
mutate(departure = make_datetime(year = year, month = month, day = day, hour = hour, min = minute))
## # A tibble: 336,776 × 6
## year month day hour minute departure
## <int> <int> <int> <dbl> <dbl> <dttm>
## 1 2013 1 1 5 15 2013-01-01 05:15:00
## 2 2013 1 1 5 29 2013-01-01 05:29:00
## 3 2013 1 1 5 40 2013-01-01 05:40:00
## 4 2013 1 1 5 45 2013-01-01 05:45:00
## 5 2013 1 1 6 0 2013-01-01 06:00:00
## 6 2013 1 1 5 58 2013-01-01 05:58:00
## 7 2013 1 1 6 0 2013-01-01 06:00:00
## 8 2013 1 1 6 0 2013-01-01 06:00:00
## 9 2013 1 1 6 0 2013-01-01 06:00:00
## 10 2013 1 1 6 0 2013-01-01 06:00:00
## # ℹ 336,766 more rows
From other types
# From date to date-time
today() %>% as_datetime()
## [1] "2023-11-07 UTC"
# From date-time to date
now() %>% as_date()
## [1] "2023-11-07"
Date-time components
Getting components
date_time <- ymd_hms("2022-10-28 18-18-18")
date_time
## [1] "2022-10-28 18:18:18 UTC"
year(date_time)
## [1] 2022
month(date_time, label = TRUE, abbr = FALSE)
## [1] October
## 12 Levels: January < February < March < April < May < June < ... < December
yday(date_time)
## [1] 301
mday(date_time)
## [1] 28
wday(date_time, label = TRUE, abbr = FALSE)
## [1] Friday
## 7 Levels: Sunday < Monday < Tuesday < Wednesday < Thursday < ... < Saturday
# Create flights_dt
make_datetime_100 <- function(year, month, day, time) {
make_datetime(year, month, day, time %% 100, time %% 100)
}
flights_dt <- flights %>%
filter(!is.na(dep_time), !is.na(arr_time)) %>%
mutate(
dep_time = make_datetime_100(year, month, day, dep_time),
arr_time = make_datetime_100(year, month, day, arr_time),
sched_dep_time = make_datetime_100(year, month, day, sched_dep_time),
sched_arr_time = make_datetime_100(year, month, day, sched_arr_time)
) %>%
select(origin, dest, ends_with("delay"), ends_with("time"))
flights_dt %>%
transmute(wday = wday(dep_time, label = TRUE)) %>%
ggplot(aes(wday)) +
geom_bar()

Rounding
# floor_date for rounding down
flights_dt %>%
mutate(week = floor_date(dep_time, "month")) %>%
select(dep_time, week) %>%
sample_n(10)
## # A tibble: 10 × 2
## dep_time week
## <dttm> <dttm>
## 1 2013-06-08 21:21:00 2013-06-01 00:00:00
## 2 2013-08-19 03:03:00 2013-08-01 00:00:00
## 3 2013-05-03 08:32:00 2013-05-01 00:00:00
## 4 2013-08-06 00:48:00 2013-08-01 00:00:00
## 5 2013-10-13 14:38:00 2013-10-01 00:00:00
## 6 2013-07-20 09:33:00 2013-07-01 00:00:00
## 7 2013-11-28 20:20:00 2013-11-01 00:00:00
## 8 2013-06-11 10:58:00 2013-06-01 00:00:00
## 9 2013-05-26 15:15:00 2013-05-01 00:00:00
## 10 2013-10-24 10:34:00 2013-10-01 00:00:00
# ceiling_date for rounding up
flights_dt %>%
mutate(week = ceiling_date(dep_time, "month")) %>%
select(dep_time, week) %>%
sample_n(10)
## # A tibble: 10 × 2
## dep_time week
## <dttm> <dttm>
## 1 2013-08-07 00:48:00 2013-09-01 00:00:00
## 2 2013-05-10 11:35:00 2013-06-01 00:00:00
## 3 2013-04-21 13:13:00 2013-05-01 00:00:00
## 4 2013-03-12 07:31:00 2013-04-01 00:00:00
## 5 2013-05-28 04:04:00 2013-06-01 00:00:00
## 6 2013-08-17 05:53:00 2013-09-01 00:00:00
## 7 2013-10-05 19:43:00 2013-11-01 00:00:00
## 8 2013-05-22 07:31:00 2013-06-01 00:00:00
## 9 2013-05-10 10:58:00 2013-06-01 00:00:00
## 10 2013-01-14 08:56:00 2013-02-01 00:00:00
Setting Components
flights_dt %>%
mutate(dep_hour = update(dep_time, yday = 1)) %>%
select(dep_time, dep_hour) %>%
sample_n(10)
## # A tibble: 10 × 2
## dep_time dep_hour
## <dttm> <dttm>
## 1 2013-04-03 13:37:00 2013-01-01 13:37:00
## 2 2013-11-15 22:46:00 2013-01-01 22:46:00
## 3 2013-03-07 09:33:00 2013-01-01 09:33:00
## 4 2013-06-21 00:24:00 2013-01-01 00:24:00
## 5 2013-11-29 04:52:00 2013-01-01 04:52:00
## 6 2013-03-28 15:15:00 2013-01-01 15:15:00
## 7 2013-03-26 12:12:00 2013-01-01 12:12:00
## 8 2013-09-29 07:07:00 2013-01-01 07:07:00
## 9 2013-01-19 01:01:00 2013-01-01 01:01:00
## 10 2013-12-05 07:31:00 2013-01-01 07:31:00
Time spans