Parameters

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08

# Parameters

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# <center>Parameters in RStudio</center>

1

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# <center>Knit with Parameters</center>

???
This uses {shiny} and may be prompted to install for use

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# <center>Inline Parameters</center>

.pull-left[
Report relates to Series ``` `r params$series` ```

]

.pull-right[
![Screenshot of the rendered html where code is now shown as text "Series 1"](images/inline-parameter.PNG)
]

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# <center>R code Parameters</center>
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# <center>R code Parameters</center>

.pull-left[

```r

series_ratings <- ratings %>% 
* filter(series == params$series)

```
]

.pull-right[

```r
ratings %>% 
 filter(series == params$series) %>% 
 head(5)
#> # A tibble: 5 x 11
#> series episode uk_airdate viewers_7day viewers_28day network_rank channels_rank bbc_iplayer_requests episode_count
#> <dbl> <dbl> <date> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 1 1 2010-08-17 2.24 7 NA NA NA 1
#> 2 1 2 2010-08-24 3 3 NA NA NA 2
#> 3 1 3 2010-08-31 3 2 NA NA NA 3
#> 4 1 4 2010-09-07 2.6 4 NA NA NA 4
#> 5 1 5 2010-09-14 3.03 1 NA NA NA 5
#> # ... with 2 more variables: us_season <dbl>, us_airdate <chr>
```

]

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# <center>In chunk settings</center>

.pull-left[

```yaml
---
params:
  show_code: FALSE
---
```

]
--

.pull-right[

Also add this to the global options:

`knitr::opts_chunk$set(echo = params$show_code)`
]

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# <center>Shiny Controls</center>

2

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# <center>Shiny Controls</center>

.pull-left[
```yaml
title: "The Great British Bake Off"
output: html_document
params:
  series: 
    label: "Series numbers"
    value: 1
    input: slider
    min: 1
    max: 9
    step: 1
```
]

.pull-right[

* label: text
* value: starting point
* input: type of wizard
* min: minimum that you set
* max: maximum that you set
* step: increments (default gives smaller points that don't match data)

]

???
The params: YAML code uses {shiny} which needs to be installed.

When searching for options related to types of `input` consider adding `shiny` 
to the search.

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# Your turn

🧶 **Knit** button and `Knit with Parameters...` after each step

1. Install and add library() call for either [wesanderson](https://github.com/karthik/wesanderson)

1. Add a new parameter called `palette:` spaced like `series:`

1. Add under the parameter:

```yaml 
label: "Give this a new name?"
value: Darjeeling1
input: select
choices: [GrandBudapest1, Darjeeling1, Darjeeling2, FantasticFox1, Royal2]
```

4. Add code to the ggplot2 to change the output colours: +
  `scale_colour_manual(values = wes_palette(params$palette))`

_psst...`01-bakeoff-report-alison.Rmd` has all the code..._

_psst-psst...answer on the next slide..._

???

Issues may occur with grey pop up from shiny for some computers - possibly VPN/network issues.

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# Answer

```yaml
  palette: 
    label: "Wes Anderson palette:"
    value: GrandBudapest1
    input: select
    choices: [GrandBudapest1, Darjeeling1, Darjeeling2, FantasticFox1, Royal2]
```

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# <center>Next section...</center>