tips to tame youR dRagon

class: center, middle, inverse, title-slide

# tips to tame youR dRagon
## Hannah L. Owens
### <span class="citation">@HannahOish</span>
### 2021-06-14

---

# Does your code have you tangled up in knots?

---

# Tip 1: Take a deep breath.

.pull-left[
* When you have a problem with a complicated piece of code, take a minute to focus and clear your mind.
]

.pull-right[
<img src="https://techsupport.foreverwarm.com/wp-content/uploads/2011/03/frustrated-computer-guy.png" width=300>
]

---

# Tip 2: Start with a clean slate.

.pull-left[
* Open a new script document.
* Clear you environment.

```r
rm(list=ls())
```
]

.pull-right[
<img src="https://www.bigimmigrationlawblog.com/wp-content/uploads/sites/365/2020/11/iStock-1023471968-330x248.jpg" width=300>
]

---

# Tip 3: Be patient

.pull-left[
* Go through the code *one* line at a time.
* Highlight, then hit "Control" + "Enter" or "Command" + "Return"
]

.pull-right[
<img src="https://upload.wikimedia.org/wikipedia/commons/a/ab/Enter-key.jpg" width=300>
]

---

# Tip 4: Keep your lines short

.pull-left[
* No one has ever won an award for shortest R code (that I know of)
* Make a series of simple statements.
]

.pull-right[

```r
# Good
a <- "one"
b <- "two"
d <- "three"
test <- c(a,b,d)
print(test)

#Bad
print(paste(c(a="one", b="two", d="three")))
```
]

---

# Tip 5: Comment early, Comment often

.pull-left[
* Use them for metadata
* Explain code chunks
* Keep them brief
* Keep them relevant
* Keep it constructive
* Can be used to debug
* OK, maybe don't use them ALLLL the time
]

.pull-right[
<img src="https://img.devrant.com/devrant/rant/c_662893_Sw1f4.jpg"  height=400>
]

---

# Tip 6: Use print() to show exactly what is happening and when
.pull-left[

```r
testFunction <- function(y){
  if (y %% 2==0){
    return("notOdd")
  } else return()
}

x <- c()
for(i in 1:3){
  print(i)
  print("executing function")
  newI <- testFunction(i)
  print(paste("newI: ", newI))
  print("appending new i")
  x <- c(x,newI)
  print(x)
}
```
]

.pull-right[

```
## [1] 1
## [1] "executing function"
## [1] "newI:  "
## [1] "appending new i"
## NULL
## [1] 2
## [1] "executing function"
## [1] "newI:  notOdd"
## [1] "appending new i"
## [1] "notOdd"
## [1] 3
## [1] "executing function"
## [1] "newI:  "
## [1] "appending new i"
## [1] "notOdd"
```
]

---

# Tip 7: Use unique indexes for every loop
.pull-left[
* Do not use `i` as a universal index
* If you don't change the index for every loop, you could accidentally recycle something
* Also it will turn nested loops into a hot mess in no time flat.
]

.pull-right[
<img src="https://live.staticflickr.com/7229/7162673224_d417dce68a_z.jpg"  height=400>
]

---

# Tip 8: Break out of the loop!
.pull-left[
* Turn your loops into functions
* Functions are easier to debug
* Functions are faster
]

.pull-right[
<img src="https://freshstitches.com/wp-content/uploads/2012/11/cut-loop-stitch-1024x768.jpg"  height=400>
]

---

# Tip 9: If you *have* to loop, make sure your code works first
.pull-left[
* Go through it line by line
* Be patient
]

.pull-right[
<img src="https://i.insider.com/5b76eda93cccd123008b45d1?width=1000&format=jpeg&auto=webp"  height=400>
]
---

# Tip 10: Simplify your piping operations
.pull-left[
* Start with basic steps
* Run lines line by line
]

.pull-right[

```r
library(magrittr)
a <- seq(1,10, by = 2)

# Good
a %>% log() %>%
    diff() %>%
    exp() %>%
    round(1)

# Bad
a %>% log() %>% diff() %>% exp() %>% round(1)
```
]
---
# Tip 11: Try
.pull-left[
* You may have to loop over messy data
* try() allows the loop to keep going instead of stalling
* Skips over problem and produces error message
]

.pull-right[

```r
inputs <-  list(1, 2, 4, -5, 'oops', 0, 10)

# With try
for(input in inputs) {
  try(print(paste("log of", input, "=", log(input))))
}
```

```
## [1] "log of 1 = 0"
## [1] "log of 2 = 0.693147180559945"
## [1] "log of 4 = 1.38629436111989"
```

```
## Warning in log(input): NaNs produced
```

```
## [1] "log of -5 = NaN"
## Error in log(input) : non-numeric argument to mathematical function
## [1] "log of 0 = -Inf"
## [1] "log of 10 = 2.30258509299405"
```
]
---

# Tip 12: tryCatch
.pull-left[
* "Fancy" version of try
* You can produce custom errors and warnings that are more informative
* Wrap in a function for maximum effect
]
.pull-right[

```r
robustLog = function(x) {
  tryCatch(log(x),
           warning = function(w) {print(paste("negative argument", x))
                                    log(-x)},
           error = function(e) {print(paste("non-numeric argument", x))
                                  NaN}) 
}

for(input in inputs) {
   print(paste("robust log of", input, "=", robustLog(input)))
}
```

```
## [1] "robust log of 1 = 0"
## [1] "robust log of 2 = 0.693147180559945"
## [1] "robust log of 4 = 1.38629436111989"
## [1] "negative argument -5"
## [1] "robust log of -5 = 1.6094379124341"
## [1] "non-numeric argument oops"
## [1] "robust log of oops = NaN"
## [1] "robust log of 0 = -Inf"
## [1] "robust log of 10 = 2.30258509299405"
```
]
---
.left-column[
# Fin.
]

.right-column[
<img src="https://pyxis.nymag.com/v1/imgs/76a/792/ca8c6ae202df791dcd06c700e9650882f9-19-how-to-train-dragon.rhorizontal.w700.jpg">
]