CODEWITHSUNDEEP
pythonrandomcount
Nourolah
Nourolah

Reputation: 13

How to count number of values in the randomly generated list?

I have created a random list by below command:

import random
a=[random.randrange(0,100) for i in xrange(50)]
print a

Now, what could be the command for counting the number of values that are between 0 and 9, 10 and 19, 20 and 29, and so on.

I can print them as below:

import random
a = [random.randrange(0,100) for i in xrange(50)]
for b in a:
  if b<10:
    print b

But, I don't know how to write a command to count the number of the values after printing b. Thanks for your comments.

Upvotes: 0

Views: 175

Answers (4)

Bill Bell
Bill Bell

Reputation: 21643

In data analysis and statistics this is called 'binning'. If you poke around on the 'net for terms like 'bin' and 'bins' you'll find a plethora of pages about software and how to do this.

But a really good one uses the preeminent product for Python, numpy.

>>> import random
>>> a=[random.randrange(0,100) for i in range(50)]
>>> from numpy import histogram

In your case you need to set up the end points of the bins which are -0.5, 9.5, 19.5, 29.5, 39.5, 49.5, 59.5, 69.5, 79.5, 89.5, and 99.5. (I've chosen -0.5 for the low end only because it made my calculation easier.) histogram counts how many items fall within each of the ranges given by these numbers, taken in pairs (-0.5 to 9.5, 9.5 to 19.5, etc).

>>> bins = [-0.5+10*i for i in range(11)]
>>> hist,_ = histogram(a, bins)

And here's the result.

>>> hist
array([6, 6, 2, 6, 2, 3, 6, 9, 5, 5], dtype=int64)

Upvotes: 0

Moinuddin Quadri
Moinuddin Quadri

Reputation: 48092

You may use bisect.bisect(...) to achieve this as:

from bisect import bisect
import random

randon_nums = [random.randint(0,100) for _ in xrange(100)]

bucket = [10, 20, 30, 40, 50, 60, 70, 80, 90, 100]  # can also be created using:
                                                    #     range(10, 101, 10)

randon_nums.sort()  # sort the initial list in order to use it with `bisect`

counts = []
last_bucket_count = 0   # to track the count of numbers in last calculated bucket

for range_max in bucket:
    i = bisect(randon_nums, range_max, end_index)
    counts.append(i - last_bucket_count)
    last_bucket_count = i

Sample Run:

When the value of random_nums is:

>>> randon_nums
[0, 1, 4, 5, 5, 5, 5, 6, 7, 7, 8, 8, 10, 10, 11, 11, 12, 13, 13, 13, 16, 17, 18, 18, 18, 18, 19, 20, 21, 22, 24, 24, 25, 25, 26, 26, 26, 26, 26, 29, 30, 30, 31, 33, 37, 37, 38, 42, 42, 43, 44, 44, 47, 47, 49, 51, 52, 55, 55, 57, 57, 58, 59, 63, 63, 63, 63, 64, 64, 65, 66, 67, 68, 71, 73, 73, 73, 74, 77, 79, 82, 83, 83, 83, 84, 85, 87, 87, 88, 89, 89, 90, 92, 93, 95, 96, 98, 98, 99, 99]

the above program returns count as:

>>> counts
[  14,   14,    14,     5,     8,     8,     10,    7,    12,    8]
#   ^     ^      ^      ^      ^      ^      ^      ^      ^     ^
# 0-10  10-20  20-30  30-40  40-50  50-60  60-70  70-80  80-90  90-100

Upvotes: 0

mshsayem
mshsayem

Reputation: 18008

Just make a dictionary, enumerate and count.

>>> import random
>>> a = [random.randrange(0,100) for i in xrange(50)]
>>> a
[88, 48, 7, 92, 22, 13, 66, 38, 72, 34, 8, 18, 13, 29, 48, 63, 23, 30, 91, 40, 96, 89, 27, 8, 92, 26, 98, 83, 31, 45, 81, 4, 55, 4, 42, 94, 64, 35, 19, 64, 18, 96, 26, 12, 1, 54, 89, 67, 82, 62]
>>> counts = {}
>>> for i in a:     
        t = counts.setdefault(i/10,0)
        counts[i/10] = t + 1


>>> counts
{0: 6, 1: 6, 2: 6, 3: 5, 4: 5, 5: 2, 6: 6, 7: 1, 8: 6, 9: 7}
# Means: 0-9=> 6 numbers, 10-19=> 6 numbers etc.

Upvotes: 1

Kostia Hvorov
Kostia Hvorov

Reputation: 19

if I understood you correctly, then so:

import random
a = [random.randrange(0,100) for i in xrange(50)]
print len(filter(lambda x: 0 <= x < 10,a))
print len(filter(lambda x: 10 <= x < 20,a))

etc

Upvotes: 1

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