Imagine that you have a list of numbers and you would like to find the index of numbers meeting a certain condition (say > 3). We would then like to have the smallest index (meeting the above condition) being a multiple of a certain number (here 4). Below might be a good start. What would you suggest for the rest of the code?

a = [1, 2, 3, 1, 2, 3, 5, 8, 9, 10 ,12, 12, 15, 16]
b = 4

output = [i for i, x in enumerate(a) if x > 3]

print(output) '''

CodePudding user response：

If you want to find the minumim index, you can use the min() function:

a = [1, 2, 3, 1, 2, 3, 5, 8, 9, 10 ,12, 12, 15, 16] 
b = 4

output = [i for i, x in enumerate(a) if x > 3]

print(output, min(output))

CodePudding user response：

The indices are already obtained by the code given above. All you need to do is find the smallest index divisible by b. You can achieve it as follows:

a = [1, 2, 3, 1, 2, 3, 5, 8, 9, 10 ,12, 12, 15, 16]
b = 4
# outputGT3 = output of all numbers > 3
outputGT3 = [i for i, x in enumerate(a) if x > 3]
print(outputGT3)
# outputDBb = output of all numbers divisible by b
outputDBb = [x for i, x in enumerate(outputGT3) if x % b==0]
print(outputDBb[0])
# since outputDBb is already sorted, the 1st element is the smallest.

CodePudding user response：

This question is unrelated to lists:

a, b = 3, 4
n = a   b/2
result = n - (n%b)