Data visualization

class: center, middle, inverse, title-slide

# Data visualization
## ggplot debugging
### Ben Baumer
### SDS 192</br>Sep 16, 2020</br>(<a href="http://beanumber.github.io/sds192/lectures/mdsr_viz_06-debugging.html" class="uri">http://beanumber.github.io/sds192/lectures/mdsr_viz_06-debugging.html</a>)

---

## Function not found

- Problem: functions can't be found

```r
glimpse(storms)
```

```
## Error in glimpse(storms): could not find function "glimpse"
```

```r
my_storms <- storms %>%
  filter(year == 1995)
```

```
## Error in storms %>% filter(year == 1995): could not find function "%>%"
```

---
## Function not found (cont'd)

- Solution: load packages that provide functions

```r
library(tidyverse)
glimpse(storms)
```

```
## Rows: 10,010
## Columns: 13
## $ name        <chr> "Amy", "Amy", "Amy", "Amy", "Amy", "Amy", "Amy", "Amy", "…
## $ year        <dbl> 1975, 1975, 1975, 1975, 1975, 1975, 1975, 1975, 1975, 197…
## $ month       <dbl> 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, …
## $ day         <int> 27, 27, 27, 27, 28, 28, 28, 28, 29, 29, 29, 29, 30, 30, 3…
## $ hour        <dbl> 0, 6, 12, 18, 0, 6, 12, 18, 0, 6, 12, 18, 0, 6, 12, 18, 0…
## $ lat         <dbl> 27.5, 28.5, 29.5, 30.5, 31.5, 32.4, 33.3, 34.0, 34.4, 34.…
## $ long        <dbl> -79.0, -79.0, -79.0, -79.0, -78.8, -78.7, -78.0, -77.0, -…
## $ status      <chr> "tropical depression", "tropical depression", "tropical d…
## $ category    <ord> -1, -1, -1, -1, -1, -1, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0…
## $ wind        <int> 25, 25, 25, 25, 25, 25, 25, 30, 35, 40, 45, 50, 50, 55, 6…
## $ pressure    <int> 1013, 1013, 1013, 1013, 1012, 1012, 1011, 1006, 1004, 100…
## $ ts_diameter <dbl> NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, N…
## $ hu_diameter <dbl> NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, N…
```

---
## Package not found

- Problem: package is not installed

```r
library(imadethisup)
```

```
## Error in library(imadethisup): there is no package called 'imadethisup'
```

---
## Package not found (cont'd)

- Solution: install package

```r
install.packages("imadethisup")
library(imadethisup)
```

---
## Re-installing packages

- Problem: Unnecessary and will slow down knitting

```r
install.packages("nasaweather")
```

- Solutions:
    - ✅ delete that command
    - comment out command with `#`
    -  use `eval=FALSE`

---
## Suppress code evaluation

- Problem: want to show code but not evaluate it

```r
install.packages("nasaweather")
```

- Solution: use `eval=FALSE`

```{r, eval=FALSE}
    install.packages("nasaweather")
    ```

---
## Suppressing messages

- Problem: unwanted messages in output

```r
library(mosaic)
```

```
## Loading required package: lattice
```

```
## Loading required package: ggformula
```

```
## Loading required package: ggstance
```

```
## 
## Attaching package: 'ggstance'
```

```
## The following objects are masked from 'package:ggplot2':
## 
##     geom_errorbarh, GeomErrorbarh
```

```
## 
## New to ggformula?  Try the tutorials: 
## 	learnr::run_tutorial("introduction", package = "ggformula")
## 	learnr::run_tutorial("refining", package = "ggformula")
```

```
## Loading required package: mosaicData
```

```
## Loading required package: Matrix
```

```
## 
## Attaching package: 'Matrix'
```

```
## The following objects are masked from 'package:tidyr':
## 
##     expand, pack, unpack
```

```
## Registered S3 method overwritten by 'mosaic':
##   method                           from   
##   fortify.SpatialPolygonsDataFrame ggplot2
```

```
## 
## The 'mosaic' package masks several functions from core packages in order to add 
## additional features.  The original behavior of these functions should not be affected by this.
## 
## Note: If you use the Matrix package, be sure to load it BEFORE loading mosaic.
## 
## Have you tried the ggformula package for your plots?
```

```
## 
## Attaching package: 'mosaic'
```

```
## The following object is masked from 'package:Matrix':
## 
##     mean
```

```
## The following objects are masked from 'package:dplyr':
## 
##     count, do, tally
```

```
## The following object is masked from 'package:purrr':
## 
##     cross
```

```
## The following object is masked from 'package:ggplot2':
## 
##     stat
```

```
## The following objects are masked from 'package:stats':
## 
##     binom.test, cor, cor.test, cov, fivenum, IQR, median, prop.test,
##     quantile, sd, t.test, var
```

```
## The following objects are masked from 'package:base':
## 
##     max, mean, min, prod, range, sample, sum
```

---
## Suppressing messages (solution)

- Solution: use `message=FALSE` in chunk

```{r, message=FALSE}
    library(mosaic)
    ```

```r
library(mosaic)
```

---
## Overwriting objects of different types

- Problem: overwriting object with different type fails on second attempt

```r
my_storms <- storms %>%
  filter(year == 1995)
class(my_storms)
```

```
## [1] "tbl_df"     "tbl"        "data.frame"
```

```r
my_storms <- ggplot(my_storms, aes(x = long, y = lat)) +
  geom_point()
```

---
## Overwriting objects of different types (cont'd)

- Try to run it again...

```r
class(my_storms)
```

```
## [1] "gg"     "ggplot"
```

```r
my_storms <- ggplot(my_storms, aes(x = long, y = lat)) +
  geom_point()
```

```
## Error: `data` must be a data frame, or other object coercible by `fortify()`, not an S3 object with class gg/ggplot
```

---
## Overwriting objects (solution)

- Solution: Give plots a different name

```r
my_storm_plot <- ggplot(my_storms, aes(x = long, y = lat)) +
  geom_point()
```

---
## Continuous variable supplied to discrete scale

- Problem: `wind` is a continuous variable but `Greens` is a discrete palette

.pull-left[

```r
ggplot(
  my_storms, 
  aes(
    x = long, 
    y = lat, 
    color = wind
  )
) +
  geom_point() + 
  scale_color_brewer(
    "Greens"
  )
```

```
## Error: Continuous value supplied to discrete scale
```
]

.pull-right[
![](figures/storms-error-1.png)
]

---
## Continuous variable supplied to discrete scale

- Solution: use `scale_color_distiller()`

.pull-left[

```r
ggplot(
  my_storms, 
  aes(
    x = long, 
    y = lat, 
    color = wind
  )
) +
  geom_point() + 
* scale_color_distiller(
    "Greens"
  )
```

]

.pull-right[
![](figures/storms-blue-1.png)

]

---
## Argument name unspecified

- Problem: no error, but always get blue

.pull-left[

```r
ggplot(
  my_storms, 
  aes(
    x = long, 
    y = lat, 
    color = wind
  )
) +
  geom_point() + 
  scale_color_distiller(
    "Greens"
  )
```

]

.pull-right[
![](figures/storms-color-1.png)

]

---
## Argument name unspecified

- Solution: specify `palette` argument name

.pull-left[

```r
ggplot(
  my_storms, 
  aes(
    x = long, 
    y = lat, 
    color = wind
  )
) +
  geom_point() + 
  scale_color_distiller(
*   palette = "Greens"
  )
```

]

.pull-right[
![](figures/storms-green-1.png)
]

---
## `color` / `fill` mismatch

- Problem: legend shows up but colors on plot don't

.pull-left[

```r
ggplot(
  my_storms, 
  aes(
    x = long, 
    y = lat, 
    fill = wind
  )
) +
  geom_point() + 
  scale_color_distiller(
    palette = "Greens"
  )
```

]

.pull-right[
![](figures/storms-black-1.png)
]

---
## `color` / `fill` mismatch

- Solution: set `color` aesthetic instead of `fill`

.pull-left[

```r
ggplot(
  my_storms, 
  aes(
    x = long, 
    y = lat, 
*   color = wind
  )
) + 
  geom_point() + 
* scale_color_distiller(
    palette = "Greens"
  )
```
]

.pull-right[
![](figures/storms-green2-1.png)
]

---
## Colors not mapped to variable

- Problem: colors don't show up

.pull-left[

```r
ggplot(
  my_storms, 
  aes(
    x = long, 
    y = lat
  ), 
  color = wind
) +
  geom_point()
```
]

.pull-right[
![](figures/storms-black2-1.png)
]

---
## Colors not mapped to variable

- Solution: put color mapping inside `aes()`

.pull-left[

```r
ggplot(
  my_storms, 
  aes(
    x = long, 
    y = lat, 
*   color = wind
  )
) +
  geom_point()
```
]

.pull-right[
![](figures/storms-blues-1.png)
]

---
## Colors not set to value

- Problem: I said `blue` but R put black

.pull-left[

```r
ggplot(
  my_storms, 
  aes(
    x = long, 
    y = lat
  ), 
  color = "blue"
) +
  geom_point()
```
]

.pull-right[
![](figures/storms-black3-1.png)
]

---
## Colors not set to value

- Solution: put value inside `geom_*()`

.pull-left[

```r
ggplot(
  my_storms, 
  aes(
    x = long, 
    y = lat
  )
) +
* geom_point(color = "blue")
```
]

.pull-right[
![](figures/storms-blue-solid-1.png)
]

---
## Colors don't vary

- Problem: `"wind"` is different than `wind`

.pull-left[

```r
ggplot(
  my_storms, 
  aes(
    x = long, 
    y = lat, 
    color = "wind"
  )
) +
  geom_point()
```
]

.pull-right[
![](figures/storms-vermillion-1.png)
]

---
## Colors don't vary

- Solution: remove quotes

.pull-left[

```r
ggplot(
  my_storms, 
  aes(
    x = long, 
    y = lat, 
*   color = wind
  )
) +
  geom_point()
```
]

.pull-right[
![](figures/storms-blues2-1.png)
]

---
## Object not found

- Problem: `windspeed` does not exist

.pull-left[

```r
ggplot(
  my_storms, 
  aes(
    x = long, 
    y = lat, 
    color = windspeed
  )
) +
  geom_point()
```

```
## Error in FUN(X[[i]], ...): object 'windspeed' not found
```
]

.pull-right[
![](figures/storms-error2-1.png)
]

---
## Object not found

- Solution: spell the name of the variable correctly

.pull-left[

```r
ggplot(
  my_storms, 
  aes(
    x = long, 
    y = lat, 
*   color = wind
  )
) +
  geom_point()
```
]

.pull-right[
![](figures/storms-blues3-1.png)
]

```r
names(my_storms)
```

```
##  [1] "name"        "year"        "month"       "day"         "hour"       
##  [6] "lat"         "long"        "status"      "category"    "wind"       
## [11] "pressure"    "ts_diameter" "hu_diameter"
```

---
## Cannot add ggproto object together

- Problem: `+` operator has to be at end of line

.pull-left[

```r
ggplot(
  my_storms, 
  aes(
    x = long, 
    y = lat, 
    color = wind
  )
)
```

```r
+ geom_point()
```

```
## Error: Cannot use `+.gg()` with a single argument. Did you accidentally put + on a new line?
```
]

---
## Cannot add ggproto object together

- Solution: move `+` operator to end of line

.pull-left[

```r
ggplot(
  my_storms, 
  aes(
    x = long, 
    y = lat, 
    color = wind
  )
*) +
  geom_point()
```
]

.pull-right[
![](figures/storms-blues4-1.png)
]

---
## Unexpected SPECIAL

- Problem: pipe operator has to be at end of line

```r
my_storms <- storms 
  %>% filter(year == 1995)
```

```
## Error: <text>:2:3: unexpected SPECIAL
## 1: my_storms <- storms 
## 2:   %>%
##      ^
```

---
## Unexpected SPECIAL

- Solution: move pipe operator to end of line

```r
my_storms <- storms %>% 
  filter(year == 1995)
```