Exploring Python Lambda Syntax with Prime Number Filtering and Heart‑Shape ASCII Art

The author describes learning Python's lambda syntax by re‑implementing a prime‑number filtering algorithm. The approach creates a long list of numbers and recursively filters out multiples using a lambda function, revealing a deeper understanding of Python's concise expression.

Below is the full Python code for the prime‑number filter:

i = 0
a = range(2, 20)

def test(sss):
    global i
    if i >= len(sss):
        return sss
    re = list(filter(lambda x: True if (a[i] == x) else (x % a[i] != 0), sss))
    i += 1
    return test(re)

c = test(a)
print(c)

After experimenting with the lambda expression, the author also refactors a one‑line Python program that prints a heart‑shaped pattern. By separating loops and conditionals, the code becomes clearer while still showcasing Python's powerful syntax.

The heart‑shape printing code is presented below:

print'
'.join([''.join([( 'Love'[(x - y) % 4] if ((x * 0.05) ** 2 + (y * 0.1) ** 2 - 1) ** 3 - (x * 0.05) ** 2 * (y * 0.1) ** 3 <= 0 else ' ') for x in range(-30, 30)]) for y in range(15, -15, -1)])

for y in range(15, -15, -1):
    line = []
    for x in range(-30, 30):
        if ((x * 0.05) ** 2 + (y * 0.1) ** 2 - 1) ** 3 - (x * 0.05) ** 2 * (y * 0.1) ** 3 <= 0:
            line.append('Love'[(x - y) % 4])
        else:
            line.append(" ")
    l = "".join(line)
    print l

The resulting output is displayed as an image of the heart shape, illustrating the visual effect of the algorithm.