Date Night

# Date Night
## using lubridate to work with dates in R
### Jen Richmond
### 2021-12-10

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# Useful links

Code along...[https://rstudio.cloud/project/1817769](https://rstudio.cloud/project/1817769)

Slides...[https://jennyslides.netlify.app/lubridate/](https://jennyslides.netlify.app/lubridate/)

🐦 @allisonhorst

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class: inverse, center, middle

# The Plan

### an opinionated guide to learning new things in R

### 3 things I learned about lubridate

### how you can help others learn new things

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# an opinionated guide to learning new things in R

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# learning new things in R

The best thing about open source software like R is that there are SO many learning resources.

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# learning new things in R

The ~~best~~ worst thing about open source software like R is that there are SO many learning resources.

## too many choices...

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image credit: [Daniela Procida PyCon](https://www.youtube.com/watch?v=t4vKPhjcMZg&t=478s)

???

tutorial = learning oriented, lessons that take the reader by the hand through a series of steps to complete a project/exercise, show the beginner can achieve something meaningful

how to guide = problem oriented, guides that take the reader through the steps required to solve a common problem, recipes/directions to do something specific

reference = technical descriptions of the machinery and how to operate it

discussion = explanations that clarify and illuminate a particular topic, background, context, explain why things are the way they are.

---

image credit: [Daniela Procida PyCon](https://www.youtube.com/watch?v=t4vKPhjcMZg&t=478s)

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image credit: [Daniela Procida PyCon](https://www.youtube.com/watch?v=t4vKPhjcMZg&t=478s)

---

image credit: [Daniela Procida PyCon](https://www.youtube.com/watch?v=t4vKPhjcMZg&t=478s)

---

image credit: [Daniela Procida PyCon](https://www.youtube.com/watch?v=t4vKPhjcMZg&t=478s)

---

# in the context of R...

### tutorials

- books
  + [R for Data Science](https://r4ds.had.co.nz/)
  + [Learning Stats w R](https://learningstatisticswithr.com/)
- courses
  + [RYouWithMe](www.rladiessydney.org/RYouWithMe)
  + [Data Science in a Box](https://datasciencebox.org/)
- primers 
  + [RStudio Cloud](https://rstudio.cloud/learn/primers)

]

### how to guides

- blogs
  + [Rebecca Barter purrr](http://www.rebeccabarter.com/blog/2019-08-19_purrr/)
  + [Alison Hill blogdown](https://alison.rbind.io/post/2017-06-12-up-and-running-with-blogdown/)
  + [Suzan Baert dpylr](https://suzan.rbind.io/categories/tutorial/)
  + [Jen Richmond IDHTG](http://jenrichmond.rbind.io/post/idhtg-how-to-use-colour-palettes-with-ggplot/)

]

---

# in the context of R...

### discussion

- journal papers
  + [Hadley Wickham re tidyverse ](https://joss.theoj.org/papers/10.21105/joss.01686)
  + [Hadley Wickham re tidy data ](https://www.jstatsoft.org/article/view/v059i10)
  + [Jenny Bryan re version control ](https://peerj.com/preprints/3159/)
  + [Kara Woo re spreadsheets](https://www.tandfonline.com/doi/full/10.1080/00031305.2017.1375989)

]

### reference

- package documentation
  + CRAN docs
  + package vignette 
  + cheat sheets

]

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# my opinion

skip tutorials and go straight to "how to" guides

image credit: https://documentation.divio.com/introduction/

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# why?
# tutorials lack an interesting context/problem

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# without context/problem...

---

]

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# how I learned lubridate

# first google...

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#.... I hit GOLD

[Julia Silge blog](https://juliasilge.com/blog/lubridate-london-stage/)

- great data set (London theatre from 1600) 
- solves common date problems
  + make characters into dates
  + plot by `year()`, `month()`, `wday()`
  + work with time spans
  
  
]

🐦 @juliasilge

]
  
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# My learning plan

Find a cool dataset and copy Julia.

dataset = [COVID testing rates NSW](https://data.nsw.gov.au/data/dataset/nsw-covid-19-tests-by-age-range/resource/28730d42-675b-4573-ad71-8156313c73a1)

]

SMH: Sept 15 2020

]

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# 3 things I learned about lubridate

### 1. plotting with date components

### 2. converting characters to dates

### 3. how to make R read your dates as dates

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### 1. plotting with date components

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# date plots

Use date components within `group_by()` + `summarise()` or within `ggplot()` using...

### `year()` 
### `month()` 
### `day()` 
### `wday()`

]

]

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Let's code... jump into [RStudio Cloud](https://rstudio.cloud/project/1817769)

https://rstudio.cloud/project/1817769

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### 2. converting characters to dates

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# So R thinks your dates are characters...

If your dates are in a consistent format, you can use...

### `ymd()`

### `mdy()`

### `dmy()`

... to convert characters to dates

]

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Let's code... jump into [RStudio Cloud](https://rstudio.cloud/project/1817769)

https://rstudio.cloud/project/1817769

---

### 3. how to make R read your dates as dates

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# if only it were consistent...

Why did the covid testing data parse as dates...

]

... but the Taylor/Beyonce data did not?

]

---

```r
sales <- read_csv(here::here("data", "sales.csv"))

sales$released[[1]]
```

```
## [1] "October 24, 2006"
```

```r
tests <- read_csv(here::here("data", "totaltests.csv"))

tests$test_date[[1]]
```

```
## [1] "2020-03-09"
```

# my hypothesis

Dates that are in year-month-day format (ISO 8601) will always parse as dates

---

# collecting data to test my hypothesis

google form:
enter your birthday 3 times

- as you like
- using a calendar widget
- in year-month-day format (ISO 8601)

]

]

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# Which dates does R think are dates?

### it depends....

---

#### using googlesheets4 package

- free date = list
- template date = date 😄
- iso date = char

#### from .xlsx

- free date = char
- template date = date 😄
- iso date = char

]

#### from .csv

- free date = char
- template date = char
- iso date = date 😠

]

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# what to do with dates in a million formats?

```r
diff_dates <- read_csv(here::here("data", "diffdatedata.csv")) %>%
  select(free_date)

head(diff_dates)
```

```
## # A tibble: 6 × 1
##   free_date    
##   <chr>        
## 1 30 June 1978 
## 2 17 Feb, 2011 
## 3 March 25 2014
## 4 1977/7/11    
## 5 4 Sep 1981   
## 6 11/7/1987
```

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# breathe...

## there are really only 3 formats

`dmy()`

`ymd()`

`mdy()`

And `parse_date_time()` is your friend...

---

```r
diff_dates <- diff_dates %>%
  mutate(free_date_parsed = parse_date_time(free_date, c("ymd", "mdy", "dmy")))

head(diff_dates, 8)
```

```
## # A tibble: 8 × 2
##   free_date     free_date_parsed   
##   <chr>         <dttm>             
## 1 30 June 1978  1978-06-30 00:00:00
## 2 17 Feb, 2011  2011-02-17 00:00:00
## 3 March 25 2014 2014-03-25 00:00:00
## 4 1977/7/11     1977-07-11 00:00:00
## 5 4 Sep 1981    1981-09-04 00:00:00
## 6 11/7/1987     1987-07-11 00:00:00
## 7 sep 11 77     1977-09-11 00:00:00
## 8 6th july 67   2067-07-06 00:00:00
```

- `parse_date_time()` failed to parse when there was no year.

- it made an error when the year was only 2 digits.

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# Take home message

Lubridate is full of functions that make working with dates in R easier

- Use date components in ggplot with...
  + `day()`, `wday()`, `month()`, `year()`

- Convert characters to dates with...
  + `dmy()`, `mdy()`, `ymd()`

- Whether R will recognise your dates depends on
  + what format they are in
  + AND where you are reading them from

BUT `parse_date_time()` does a pretty good job 😄

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# how you can help others learn new things

### come to our Show and Tell events (next Nov 17)

### offer to teach an R-Ladies Sydney workshop

### and blog while you are learning

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# Read about my learning process

My blog = [www.jenrichmond.rbind.io](http://www.jenrichmond.rbind.io/)

1. [first google](http://jenrichmond.rbind.io/post/lubridate-month-wday/)

2. [`wday()` `month()`](http://jenrichmond.rbind.io/post/lubridate-month-wday/)

3. [converting characters](http://jenrichmond.rbind.io/post/converting-characters-to-dates/)

4. [parsing dates automatically](http://jenrichmond.rbind.io/post/parsing-dates-automatically/)

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# thank you !

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