Use for loop or multiple prints?

March 1, 2022

What programming style should I use?

...
print(1)
print(2)

...
for i in range(1, 3):
    print(i)

The output is the same 1 and on the next line 2, but which version should I use as a Python programmer?

I mean the first version is redundant or not?

>Solution :

It depends.

There is an old rule "three or more, use for". (source)

On the other hand, sometimes unrolling a loop can offer a speed-up. (But that’s generally more true in C or assembly.)

You should do what makes your program more clear.

For example, in the code below, I wrote out the calculations for the ABD matrix of a fiber reinforced composite laminate, because making nested loops would make it more complex in this case;

    for la, z2, z3 in zip(layers, lz2, lz3):
        # first row
        ABD[0][0] += la.Q̅11 * la.thickness  # Hyer:1998, p. 290
        ABD[0][1] += la.Q̅12 * la.thickness
        ABD[0][2] += la.Q̅16 * la.thickness
        ABD[0][3] += la.Q̅11 * z2
        ABD[0][4] += la.Q̅12 * z2
        ABD[0][5] += la.Q̅16 * z2
        # second row
        ABD[1][0] += la.Q̅12 * la.thickness
        ABD[1][1] += la.Q̅22 * la.thickness
        ABD[1][2] += la.Q̅26 * la.thickness
        ABD[1][3] += la.Q̅12 * z2
        ABD[1][4] += la.Q̅22 * z2
        ABD[1][5] += la.Q̅26 * z2
        # third row
        ABD[2][0] += la.Q̅16 * la.thickness
        ABD[2][1] += la.Q̅26 * la.thickness
        ABD[2][2] += la.Q̅66 * la.thickness
        ABD[2][3] += la.Q̅16 * z2
        ABD[2][4] += la.Q̅26 * z2
        ABD[2][5] += la.Q̅66 * z2
        # fourth row
        ABD[3][0] += la.Q̅11 * z2
        ABD[3][1] += la.Q̅12 * z2
        ABD[3][2] += la.Q̅16 * z2
        ABD[3][3] += la.Q̅11 * z3
        ABD[3][4] += la.Q̅12 * z3
        ABD[3][5] += la.Q̅16 * z3
        # fifth row
        ABD[4][0] += la.Q̅12 * z2
        ABD[4][1] += la.Q̅22 * z2
        ABD[4][2] += la.Q̅26 * z2
        ABD[4][3] += la.Q̅12 * z3
        ABD[4][4] += la.Q̅22 * z3
        ABD[4][5] += la.Q̅26 * z3
        # sixth row
        ABD[5][0] += la.Q̅16 * z2
        ABD[5][1] += la.Q̅26 * z2
        ABD[5][2] += la.Q̅66 * z2
        ABD[5][3] += la.Q̅16 * z3
        ABD[5][4] += la.Q̅26 * z3
        ABD[5][5] += la.Q̅66 * z3
        # Calculate unit thermal stress resultants.
        # Hyer:1998, p. 445
        Ntx += (la.Q̅11 * la.αx + la.Q̅12 * la.αy + la.Q̅16 * la.αxy) * la.thickness
        Nty += (la.Q̅12 * la.αx + la.Q̅22 * la.αy + la.Q̅26 * la.αxy) * la.thickness
        Ntxy += (la.Q̅16 * la.αx + la.Q̅26 * la.αy + la.Q̅66 * la.αxy) * la.thickness
        # Calculate H matrix (derived from Barbero:2018, p. 181)
        sb = 5 / 4 * (la.thickness - 4 * z3 / thickness ** 2)
        H[0][0] += la.Q̅s44 * sb
        H[0][1] += la.Q̅s45 * sb
        H[1][0] += la.Q̅s45 * sb
        H[1][1] += la.Q̅s55 * sb
        # Calculate E3
        c3 += la.thickness / la.E3