计算列表中的各种实例

Question

I've hit a wall here for a project i'm completing. i've tried while loops, for loops, counts etc. i need to count instances of numbers eg. (<=10)(>10 & <=20) etc etc

data=[99,50,19,67,85,87,50,45,51,72,64,69,59,17,22]

while grades >=10:
    counter=0
for grades in data:
    grades[counter]=grades+1
    counter+=1

This isnt the only attempt, rather this was my last attempt before i lost my head.

i've encountered many threads here which havent solved this. it more than likely just me

Will appreciate any help

edit - i wasnt clear, as advised by the below user. i require my results to look something similar to the below

grades <= 10 - 2
grades >10 & <=20 - 5
grades >20 & <=30 - 7
etc
etc
etc

Answer 1

Using numpy :

import numpy as np

data=np.array([99,50,19,67,85,87,50,45,51,72,64,69,59,17,22])

len(data[(data>20) & (data<=30)])
#result: 1
len(data[(data>=10)])
#result: 15