March 09, 2018 / Viewed: 198060 / Comments: 0 / Edit

Examples of how to create a list of numbers in python using list comprehensions or built-in functions list():

To create a list of integers between 0 and N, a solution is to use the range(N) function:

`>>> l = [i for i in range(10)]`

`>>> l`

`[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]`

`>>> l = list(range(10))`

`>>> l`

`[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]`

To create a list of integers between N and M (with M>N), the function range() can still be used:

`>>> l = [i for i in range(25,35)]`

`>>> l`

`[25, 26, 27, 28, 29, 30, 31, 32, 33, 34]`

`>>> l = list(range(25,35))`

`>>> l`

`[25, 26, 27, 28, 29, 30, 31, 32, 33, 34]`

To create a list of floats between (N,M) with a given step, a solution is to use the numpy function called arange:

`>>> import numpy as np`

`>>> l = [i for i in np.arange(2,8,0.5)]`

`>>> l`

`[2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5]`

`>>> l = list(np.arange(2,8,0.5))`

`>>> l`

`[2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5]`

To create a list of floats between (N,M) with a given number of elementsa solution is to use the numpy function linspace:

`>>> import numpy as np`

`>>> l = [i for i in np.linspace(12,16,8)]`

`>>> l`

`[12.0, 12.571428571428571, 13.142857142857142, 13.714285714285714, 14.285714285714285, 14.857142857142858, 15.428571428571429, 16.0]`

`>>> l = list(np.linspace(12,16,8))`

`>>> l`

`[12.0, 12.571428571428571, 13.142857142857142, 13.714285714285714, 14.285714285714285, 14.857142857142858, 15.428571428571429, 16.0]`

The python function randint can be used to generate a random integer in a chosen interval [a,b]:

`>>> import random`

`>>> random.randint(0,10)`

`7`

`>>> random.randint(0,10)`

`0`

A list of random numbers can be then created using python list comprehension approach:

`>>> l = [random.randint(0,10) for i in range(5)]`

`>>> l`

`[4, 9, 8, 4, 5]`

Another solution is to use randrange function (except that can specify a step if you need):

`>>> l = [random.randrange(0,10) for i in range(5)]`

`>>> l`

`[1, 7, 4, 3, 1]`

`>>> l = [random.randrange(0,10,2) for i in range(5)]`

`>>> l`

`[2, 4, 4, 6, 0]`

A third solution is to create a list of random numbers with no repetition, is to use random.sample function

`>>> l = random.sample(range(1,100), 10)`

`>>> l`

`[89, 56, 87, 51, 46, 25, 52, 44, 10, 32]`

Liens | Site |
---|---|

List Comprehensions | python doc |

list() | python doc |

Python - Create list with numbers between 2 values? | stackoverflow |

How can I generate a list of consecutive numbers? | stackoverflow |

numpy.linspace | scipy doc |

numpy.arange | scipy doc |

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