How Can I Efficiently Compare Multiple Python Variables to a Single Value?

Testing Multiple Variables for Equality Against a Single Value in Python

The task described involves comparing multiple variables (x, y, z) to a specific integer and generating a list of corresponding letters. The provided code attempts to achieve this using a series of if-elif statements, but a more concise and efficient approach is available.

Solution

The misunderstanding lies in the evaluation of boolean expressions, which are handled as separate expressions, not as a collective comparison. To test multiple variables against a single value, the following syntax should be used:

if 1 in (x, y, z):

Explanation

• in operator: Checks whether the value on the left-hand side is in the set specified on the right-hand side.
• Set: A collection of unique and unordered elements enclosed in curly braces ({ }). In this case, {x, y, z} creates a set of the given variables.

Using the in operator guarantees that only one variable needs to be tested for equality against the integer (in this case, 1), significantly simplifying the code.

Advantages

• Concise: Reduces the number of lines of code required.
• Efficient: Uses a single boolean expression to evaluate multiple variables, resulting in faster execution times.
• Generalizable: Can be easily modified to test against different values or within different sets of variables.

Therefore, the revised code to generate the desired list becomes:

x = 0
y = 1
z = 3
mylist = []

if 1 in {x, y, z}:
    mylist.append("c")
if 2 in {x, y, z}:
    mylist.append("d")
if 3 in {x, y, z}:
    mylist.append("f")

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