If-else statements in R Programming - Step-by-Step Execution

Concept Flow - If-else statements

Evaluate condition

↓

Is condition TRUE?

No→Execute else block

Yes↓

Execute if block

↓

End

The program checks a condition. If true, it runs the 'if' part; if false, it runs the 'else' part, then continues.

Execution Sample

R Programming

x <- 7
if (x > 5) {
  result <- "big"
} else {
  result <- "small"
}

Checks if x is greater than 5; assigns 'big' if true, otherwise 'small'.

Execution Table

Step	Condition (x > 5)	Result	Branch Taken	Variable 'result'
1	7 > 5	TRUE	if block	"big"
2	End of if-else	-	-	"big"

💡 Condition is TRUE, so 'if' block runs and 'result' is set to 'big'.

Variable Tracker

Variable	Start	After Step 1	Final
x	7	7	7
result	undefined	"big"	"big"

Key Moments - 2 Insights

Why does the else block not run when x is 7?

Because the condition x > 5 is TRUE at step 1, so the if block runs and the else block is skipped.

What happens if the condition is FALSE?

The else block runs instead, setting 'result' to 'small' as shown by the branch taken in the execution table.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of 'result' after step 1?

A "big"

B "small"

C undefined

D 7

💡 Hint

Check the 'Variable result' column in row for step 1 in the execution table.

At which step does the program decide which branch to take?

A Step 2

B Step 1

C Before Step 1

D After Step 2

💡 Hint

Look at the 'Condition' and 'Branch Taken' columns in the execution table.

If x was 3 instead of 7, what would 'result' be after step 1?

A undefined

B "big"

C "small"

D 3

💡 Hint

Think about the condition x > 5 and which branch runs when it is FALSE.

Concept Snapshot

If-else statements in R:
if (condition) {
  # code if TRUE
} else {
  # code if FALSE
}
Runs one block based on condition truth.
Useful for decision making.

Full Transcript

This visual execution shows how an if-else statement works in R. The program checks if x is greater than 5. Since x is 7, the condition is TRUE, so it runs the 'if' block and sets result to 'big'. The else block is skipped. Variables x and result are tracked before and after execution. Key moments clarify why the else block does not run and what happens if the condition is false. The quiz tests understanding of variable values and branch decisions based on the execution table.