-"hello" == "hello"
+
+[1] TRUEConditionals
+-
+
- You can write code that runs only if an ‘if statement’ is true
+
-
+
- Otherwise that chunk of code is skipped! +
+
+
+
+-
+
- This allows you to write flexible code that can handle any outcome that you can anticipate!
+
-
+
- Particularly useful for subsetting data based on the contents of a column +
+
+
+
+-
+
- These ‘if statements’ are called conditionals +
+
+
+-
+
- The answer to a conditional must be either
TRUEorFALSE
+
Fundamentals: EQUAL
+-
+
- Are two things exactly equal? +
+
+
+
+
+
-
+
- Uses
==operator +-
+
- Just two equal signs +
+
Fundamentals: OR
+-
+
- Are any of these conditions met? +
+
+
-
+
- Uses
|operator +-
+
- Shift +
\on keyboard
+
+ - Shift +
Fundamentals: AND
+-
+
- Are all of the conditions met? +
+
+
-
+
- Uses
&operator +-
+
- Shift + 7 on keyboard +
+
Conditionals: EQUAL, OR, & AND
+Fundamentals: Summary
+
+
+
EQUAL
+-
+
- Are two things exactly equal? +
+
+
-
+
- Uses
==operator +-
+
- Just two equal signs +
+
+
+OR
+-
+
- Are any of these conditions met? +
+
+
-
+
- Uses
|operator +-
+
- Shift +
\on keyboard
+
+ - Shift +
Practice: Fundamental Conditionals
+
-
+
- We’ll use the base R
subsetfunction with thepeng_dfobject +-
+
- If needed, consult the help file for more details (
?subset)
+
+ - If needed, consult the help file for more details (
+
+
+-
+
- Subset
peng_dfto only Adelie penguins (and assign to asub_v1object) +-
+
- I.e.,
species == "Adelie"
+
+ - I.e.,
More Practice: Fundamental Conditionals
+
-
+
- Subset
peng_dfto Adelie or Biscoe penguins +-
+
- Assign this subset to
sub_v2object
+
+ - Assign this subset to
+
+
-
+
- Subset
peng_dfto only male Gentoo penguins +-
+
- Assign to
sub_v3object
+
+ - Assign to
Discussion: Conditionals
+-
+
- We’ve covered EQUAL, OR, and AND
+
-
+
==,|, or&
+
+
+
-
+
- What unanswered questions do you have? +
+
+
-
+
- What other types of conditional statements would be useful?
+
-
+
- Think about it in the context of wanting to subset some data +
+
Numeric Conditionals
+-
+
- For numbers, we can use greater/less than conditionals! +
+
+
+-
+
- Greater / less than are expressed as normal
+
-
+
>and<
+
+
+
+
-
+
- Adding ‘or equal to’ is done by adding an equal sign
+
-
+
>=and<=
+
+
Practice: Numeric Conditionals
+-
+
- Subset
peng_dfto only penguins with a bill length greater than 40 mm +-
+
- Assign to
sub_v7
+
+ - Assign to
+
+
-
+
- Subset
peng_dfto only penguins with a body mass less than or equal to 4,000 g +-
+
- Assign to
sub_v8
+
+ - Assign to
Temperature Check
@@ -884,13 +1143,15 @@Upcoming Due Dates
Due before lab
(By midnight)
-
-
- Muddiest Point #x +
- Muddiest Point #2 +
- Read Excuse me, do you have a moment to talk about version control?
Due before lecture
(By midnight)
-
-
- X +
- Homework #2 +
- Read the British Ecological Society’s Reproducible Code Guide (p.20-25)
(By midnight)
Bonus Conditionals
OR with >2 Options
+-
+
- OR conditionals with many options get cumbersome quickly
+
-
+
- E.g.,
x == 1 | x == 2 | x == 3 | x == 4 …
+
+ - E.g.,
+
+
+-
+
- We can use concatenation and the
%in%operator to simplify this!
+
+
+
-
+
%in%is effectively “if any of <this vector> matches the value” +-
+
- E.g.,
x %in% c(1, 2, 3, 4, …)
+
+- E.g.,
Conditionals: NOT
+-
+
- You can also exclude based on conditions
+
-
+
- Two different ways of doing this +
+
+
+
+-
+
- For one / a few options: use
!=for “not equal to” +-
+
- E.g.,
x != 10
+
+ - E.g.,
+
+
+-
+
- Can be combined with
%in%to exclude a set of options +-
+
- E.g.,
!x %in% c(...)
+ - Note the exclamation mark is before the object +
+ - E.g.,
Practice: Advanced Conditionals
+-
+
- Subset
peng_dfis species is any of “Adelie”, “Gentoo”, or “Chinstrap” +-
+
- Use the
%in%operator
+
+ - Use the
+
+
-
+
- Subset
peng_dfto all islands except “Dream”
+