# python - Generate 'n' unique random numbers within a range

ID : 10404

viewed : 21

Tags : pythonrandomuniquepython

### Top 5 Answer for python - Generate 'n' unique random numbers within a range

93

If you just need sampling without replacement:

``>>> import random >>> random.sample(range(1, 100), 3) [77, 52, 45] ``

random.sample takes a population and a sample size `k` and returns `k` random members of the population.

If you have to control for the case where `k` is larger than `len(population)`, you need to be prepared to catch a `ValueError`:

``>>> try: ...   random.sample(range(1, 2), 3) ... except ValueError: ...   print('Sample size exceeded population size.') ...  Sample size exceeded population size ``

88

Generate the range of data first and then shuffle it like this

``import random data = range(numLow, numHigh) random.shuffle(data) print data ``

By doing this way, you will get all the numbers in the particular range but in a random order.

But you can use `random.sample` to get the number of elements you need, from a range of numbers like this

``print random.sample(range(numLow, numHigh), 3) ``

77

You could add to a `set` until you reach `n`:

``setOfNumbers = set() while len(setOfNumbers) < n:     setOfNumbers.add(random.randint(numLow, numHigh)) ``

Be careful of having a smaller range than will fit in `n`. It will loop forever, unable to find new numbers to insert up to `n`

68

You could use the `random.sample` function from the standard library to select k elements from a population:

``import random random.sample(range(low, high), n) ``

In case of a rather large range of possible numbers, you could use `itertools.islice` with an infinite random generator:

``import itertools import random  def random_gen(low, high):     while True:         yield random.randrange(low, high)  gen = random_gen(1, 100) items = list(itertools.islice(gen, 10))  # Take first 10 random elements ``

After the question update it is now clear that you need n distinct (unique) numbers.

``import itertools import random  def random_gen(low, high):     while True:         yield random.randrange(low, high)  gen = random_gen(1, 100)  items = set()  # Try to add elem to set until set length is less than 10 for x in itertools.takewhile(lambda x: len(items) < 10, gen):     items.add(x) ``

50

For an HTTP-based server there is a Python script to find the server version at: http://svn.apache.org/repos/asf/subversion/trunk/tools/client-side/server-version.py

You can get the client version with

```svn --version` ``