如何获取给定百分位范围内的列表元素？

Question

I am trying to iterate over a list of elements that satisfy my percentile range without using numPy. I am approaching the problem with a simple for-loop. The answer I am receiving is of all the elements that I want but it is being repeated. Where am I lacking?

yos = [('student3', 12),
         ('student4', 14),
         ('student9', 35),
         ('student6', 43),
         ('student1', 45),
         ('student7', 47),
         ('student5', 48),
         ('student2', 78),
         ('student10', 80),
         ('student8', 98)]
        
for si in range(25, 76):
    y = len(yos)*(si/100)
    y1 = int(y+.5)
    if yos[y1-1] in yos:
    print(yos[y1-1])
        
 

Wanted output:

    ('student9', 35)
    ('student6', 43)
    ('student1', 45)
    ('student7', 47)
    ('student5', 48)

Received output:

('student9', 35)
('student9', 35)
('student9', 35)
('student9', 35)
('student9', 35)
('student9', 35)
('student9', 35)
('student9', 35)
('student9', 35)
('student9', 35)
('student6', 43)
('student6', 43)
('student6', 43)
('student6', 43)
('student6', 43)
('student6', 43)
('student6', 43)
('student6', 43)
('student6', 43)
('student6', 43)
('student1', 45)
('student1', 45)
('student1', 45)
('student1', 45)
('student1', 45)
('student1', 45)
('student1', 45)
('student1', 45)
('student1', 45)
('student1', 45)
('student7', 47)
('student7', 47)
('student7', 47)
('student7', 47)
('student7', 47)
('student7', 47)
('student7', 47)
('student7', 47)
('student7', 47)
('student7', 47)
('student5', 48)
('student5', 48)
('student5', 48)
('student5', 48)
('student5', 48)
('student5', 48)
('student5', 48)
('student5', 48)
('student5', 48)
('student5', 48)
('student2', 78)

Answer 1

Your calculation results in duplicate values.

y = len(yos)*(si/100)
y1 = int(y+.5)

y1 will be the same value for multiple iterations. y=2.6, y=2.7, y=2.8, y=2.9 all convert to 3 when you add.5 and convert it to an int.

One option would be to create a set of indices, then just print out the values at those indices.

Something like:

import math


yos = [('student3', 12),
       ('student4', 14),
       ('student9', 35),
       ('student6', 43),
       ('student1', 45),
       ('student7', 47),
       ('student5', 48),
       ('student2', 78),
       ('student10', 80),
       ('student8', 98)]


set_of_indices = set([int(math.floor(len(yos) * (si / 100))) for si in range(25, 76)])

for y in set_of_indices:
    print(yos[y])

Answer 2

z = [('student3', 12),
         ('student4', 14),
         ('student9', 35),
         ('student6', 43),
         ('student1', 45),
         ('student7', 47),
         ('student5', 48),
         ('student2', 78),
         ('student10', 80),
         ('student8', 98)]
        
for si in range(25, 75,10):
    y = (len(z)*si)/100
    y1 = int(y+.5)
    if z[y1-1] in z: print(z[y1-1])

Try the code here

It's in fact the int() function that created the problem. so the solution was to add 10 as a third parameter in range: range(25, 75,10) To understand more, please see the .range() function documentation

You've gotta also make the range be between 25 and 75 , not 76 ... So you don't have a problem with.int()