Samuel J Gurr, PhD

Boolean workshop

by Samuel J Gurr PhD 6 min read

If / Else Workshop

Click ‘Visual’ at the top of this window for the formatted experience

‘if else’ statements are a simple yet powerful tool that can demystify the ‘ones and zeros’ of coding. If you can logically reach your desired outcome from a series of true and false statement, you can do anything!

OBJECTIVE:

  • use conditional statements to control large data sets, converting values based on conditional criteria

    • a custom tutorial is provided to become familiar with if else statements!

    • a few questions for group work

  • familiarize ourselves with common logical operators

    • ! = NOT

    • & = AND (element wise)

    • | = OR (element wise)

Intro to boolean variables

  • boolean (computing definition) - a binary variable or outcome as ‘true’ or ‘false’

Conditional statements - if else statements following a boolean logic, meaning a series of binary true and false outcomes. They are are coded in R as the following:

if ( statement here ) {

outcome if true

} else { outcome if false }

Let’s give it a go shall we!

  • run line by line to understand the boolean logic (true and false)

  • change x to receive the opposite outcome

```{r intro to boolean, include=TRUE}

x = 1.1 # change me and run again below!

if (x < 1) { # if x is < than 1…

print(‘x is less than 1’) # print this message if TRUE

} else { # else means here than x is greater than one

print(‘x is greater than 1’) # print this message if FALSE

}


## Operating on if else with Operators

Problem: We have a conditional statement based on a threshold that is a likely outcome.

X=1 is the metaphorical wrench that will break our if else machine!

-   run the code below

```{r throw the wrench, some more!, include=TRUE}

x = 1 # the wrench

# our machine
if (x < 1) { # if x is < than 1…    

  print('x is less than 1') # print this message if TRUE    

} else { # else means here than x is  greater than one    

    print('x is greater than 1') # print this message if FALSE  

  }

  • “x is greater than 1” but… but… this is FALSE! (“oh no!”)

    • the if statement asks if x is less than 1 – it was not, it simply ran the remaining else output

Use operators to save us from doom

option 1: using | for OR statement

```{r help yourself with OR, some more!, include=TRUE}

x = 1 # the value that throws the metaforical wrench on our code

if (x < 1 x == 1) { # add the OR statement!

print(‘x is less than or equal to 1’) # change your output to inform yourself

} else { # else means here than x is greater than one

print(‘x is greater than 1’) # print this message if FALSE }


option 2: using `&` or AND statement

```{r help yourself with AND, include=TRUE}

x = 1

if (x < 1 & x != 1) { # add & for x not equal to 1

  print('x is less than 1') # added more information for this output

} else { # else means here than x is  greater than one

  print('x is greater than or equal to 1') # print this message if FALSE
}

What if you want to add another statement? use else if

else if - if your first if statement is false, else if provides another opportunity before defaulting to the else output

  • note you can have as many else if statements that you’s like - just remember to keep organized and logical

option 3: add else if

```{r else… if..?, some more!, include=TRUE} x = 1

if (x < 1 ) { # if x is lass than 1

print(‘x is less than 1’) # output if TRUE

} else if (x == 1) {

print(‘x is equal to 1, wrench removed - your machine lives’)

} else { # else means here than x is greater than one

print(‘x is greater than or equal to 1’) # print this message if FALSE

}


### Activity 1: The Sunday scaries (ooooo!)

#### *Imagine* it is mid-July and the weather has been beautiful and warm. You had an amazing weekend and you don't want it to end.

#### "...oh ..hmm that *muuust* be next week ..oh no!"

#### A jolt of shivers runs down your spine, it is after 5 pm on Sunday already! You just remembered you are leading a meeting tomorrow morning!

-   Objective: edit the time and your preparedness to receive the output `just blame it on the kids and stay home tomorrow`
-   Understand the `if`, `else, and else if` conditional statement with operators to solve!
-   a chunk is created below, fill the variables and learn your destiny

```{r sunday scaries, include=TRUE}
#  install.packages('lubridate') # if you do not have it already
library(lubridate) # converts the hour and minutes you input into an integer,


# assign your variables
day    =  # hmm.. what day is it?

time   =  as.numeric(hm('00:00')) # input military time, curently midnight 'hm' lubridate

ready  =   # add whether you are ready as 'yes' or 'no' o include  the quptes as a string


# run the conditional statement and learn your destiny

if (day != 'Sunday' & ready == 'no') { # the pseudosunday scaries

  print('Phew! Blissfully procrastinate more')

} else if (day == 'Sunday' & ready != 'no' & time < as.numeric(hm('17:00'))) { # almost forgot that you are awesome

  print('Oh yeah - you prepared last week! You are a badass, enjoy your time in the sun.')

} else if (day == 'Sunday' & ready != 'no' & time > as.numeric(hm('17:00'))) {

  print('Popcorn time')

} else if (day == 'Sunday' & ready == 'no' & time < as.numeric(hm('17:00'))) {

  print('Palms sweaty, eyes twitching - become awkwardly quiet and stiff. You scramble to finish your wide-eyed goodbyes to your friends as you inch closer to the exit. The computer calls out to you, finish the task if your life depends on it.')

} else {

  print('Just blame it on the kids and stay home tomorrow') # print this message if FALSE
}

Activity 2: Life’s obstacles

Imagine you’re on the way to work, it’s Monday - time to show that meeting what you got!

The speed limit to work is 25 mph the whole way, if you don’t speed you will be late… you caaan’t be late again!

Careful! You need to navigate your speed, the weather, and your caffeine intake (or lack thereof) to avoid getting into an accident, a speeding ticket, or worse!

  • Objective: fit the story! use operators to edit each if, else, and else if conditional statement

  • a chunk is started below

```{r lifes obstacles, include=TRUE}

install.packages(‘lubridate’) # if you do not have it already

library(lubridate) # converts the hour and minutes you input into an integer

assign your variables

weather = # rain or shine, you choose

speed_mph = # is your foot made of feather or lead?

coffee = # yes or no; decaf or regular; your choose

what will it be you coding coder you?

if () { # you’re a caffeinated getaway driver navigating a sunny day in the burbs like a bandit

print(‘Made it safe and sound, 15 minutes early!’)

} else if () { # caffeinated or not, its pouring cats and dogs so you follow the man’s rules

print(‘Made it safe and sound, but late. Luckily, everyone was late becasue of the sudden storm.’)

} else if () { # left home like an uncaffeinated bat out of hell!

print(‘Lets hope your liscence and registration is in the glove compartment!’)

} else if () { # speeding in the rain, you hydroplaned and missed your meeting ..some say you’re still spinning

print(‘Woweeeee!’)

} else { # the weather and caffeine withdrawal spell the perfect storm to turn this car around!

print(‘Turn around and take the meeting from zoom’) } ```