More elegant way to form n-digit range of numbers - python

I need to form a range of numbers depending on input param n. If n=1 range is range(0, 10), if n=2 then range(10, 100).
I have a code, but it looks ugly, maybe there is better way.
start = 0 if n == 1 else int('1' + '0' * (n - 1))
end = 10 if n == 1 else 10 * start
for i in range(start, end):
For n=1 it should be:
range(0, 10)
[0,1,2,3,4,5,6,7,8,9]

Try this:
if n == 1:
interval = range(0, 10**n)
else:
interval = range(10**(n-1), 10**n)
If your range for n=1 is range(1,10), you can use just: range(10**(n-1), 10**n) without the if clause

>>> range(pow(10, n), pow(10, n)*10)
[1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> range(pow(10, n), pow(10, n)*10)
[10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99]

You can use pow in combination with range (in Python 2.7, use xrange, which saves you from allocating the whole list in memory):
n = 1
start = pow(10, n)
r = (range(10) if n == 1 else range(start, start * 10))
[i for i in r]
# [1, 2, 3, 4, 5, 6, 7, 8, 9]

This shows you, how you can use pow math.pow, to solve your usecase.
It does not solve every detail, but it points you in the right direction.
>>> from math import pow
>>> n = 1
>>> range(int(pow(10, n - 1)), int(pow(10, n)))
[1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> n = 2
>>> range(int(pow(10, n - 1)), int(pow(10, n)))
[10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99]
>>> n = -1
>>> range(int(pow(10, n - 1)), int(pow(10, n)))
[]
You need to make sure that n is bigger den 0 :-)
EDIT 1:
As viakondratiuk mentioned in if n is 1, it should start from 0, not 1.
EDIT 2:
You may use ** notation to avoid casting the float to int.
>>> n = 2
>>> range(10 ** (n - 1), 10 ** n)
[10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99]

Related

How do you split an array into specific intervals in Num.py for Python?

The question follows a such:
x = np.arange(100)
Write Python code to split the following array at these intervals: 10, 25, 45, 75, 95
I have used the split function and unable to get at these specific intervals, can anyone enlighten me on another method or am i doing it wrongly?
Here's both the manual way and the numpy way with split.
# Manual method
x = np.arange(100)
split_indices = [10, 25, 45, 75, 95]
split_arrays = []
for i, j in zip([0]+split_indices[:-1], split_indices):
split_arrays.append(x[i:j])
print(split_arrays)
# Numpy method
split_arrays_np = np.split(x, split_indices)
print(split_arrays_np)
And the result is (for both)
[array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]),
array([10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24]),
array([25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44]),
array([45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74]),
array([75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94])
]

Why this function returns only a digit 2 instead of numbers from 1 to 100?

def display_even_digits(a, b):
for digit in range(a, b):
if digit % 2 == 0:
return digit
print(display_even_digits(1, 101))
You are returning the first even number, you need to return all numbers. You could just find if a is even and if not add 1 and then use the step argument of range.
def display_even_digits(a, b):
return list(range(a + a % 2, b, 2))
print(display_even_digits(1, 101))
[2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100]
This is probably what you want?
def display_even_digits(a, b):
result = []
for digit in range(a, b):
if digit % 2 == 0:
result.append(digit)
return result
print(display_even_digits(1, 101))
[2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100]

Getting a syntax error when displaying a matrix in python

here is the code:
#STARTING MESSAGE
print('Any *num* is a numerator, and any *den* is a denominator. *num1* is for the first fraction, and *num2* is for the second fraction. Same thing with the denominators. Please enter num1, saying *num1 = x* with the num1 =. THIS ONLY WORKS WITH NUMBERS 1 THROUGH 100!')
#DEN1
num1 = 3
if num1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 02, 93, 94, 95, 96, 97, 98, 99, 100]:
print(now enter den1)
den1 = 34
if den1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 02, 93, 94, 95, 96, 97, 98, 99, 100]:
print(now enter num2)
#SEC == 2
num2 = 4
if num2 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 02, 93, 94, 95, 96, 97, 98, 99, 100]:
print(now enter den2)
den2 = 33
if den2 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 02, 93, 94, 95, 96, 97, 98, 99, 100]:
print(CALCULATING...)
#CALCULATING CODE
den1*num2 = secondFrac
den2*num1 = firstFrac
if firstFrac > secondFrac:
print('The first fraction is greater then the second fraction! *First_Fraction > Second_Fraction!*')
if firstFrac < secondFrac:
print('The second fraction is greater then the first fraction! *First_Fraction < Second_Fraction!*')
I am getting a syntax error with the matrixes, just saying "Syntax Error: Invalid Syntax"

Python, delete subinterval from an interval

In python, I have an interval
a = 1-100
And I have a list with intervals
b = [11-20,41-50,91-110]
Now I would like my output to be like this in python:
a-b = 1-10,21-40,51-90
You have this :
a=range(1,100)
b = [range(11,20),range(41,50),range(91,110)] #list of ranges
So you can try :
d=[]
i=a.start
for sub_range in b: #for each sub range
#get the start and stop
start=sub_range.start
end=sub_range.stop
#append range to list
d.append(range(i,start-1))
i=end+1
print(d)
[range(1, 10), range(21, 40), range(51, 90)]
You can try this
a = range(1,101)
set(a)
b = [11,12,13,14,15,16,17,18,19,20,41,42,43,44,45,46,47,48,49,50,91,92,93,94,95,96,97,98,99,100]
set(a)-set(b)
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90}
You can use more_itertoools to divide the list
import more_itertools as mit
iterable = list(d)
[list(group) for group in mit.consecutive_groups(iterable)]
Result
[[1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40], [51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90]]

Largest product out of 4 in a grid

I'm doing some project euler problems to practice more. I am at problem 11 and I keep getting the wrong answer.
Here is the list of lists:
problem_11 = [[8, 2, 22, 97, 38, 15, 0, 40, 0, 75, 4, 5, 7, 78, 52, 12, 50, 77, 91, 8],
[49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 4, 56, 62, 0],
[81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 3, 49, 13, 36, 65],
[52, 70, 95, 23, 4, 60, 11, 42, 69, 24, 68, 56, 1, 32, 56, 71, 37, 2, 36, 91],
[22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80],
[24, 47, 32, 60, 99, 3, 45, 2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50],
[32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70],
[67, 26, 20, 68, 2, 62, 12, 20, 95, 63, 94, 39, 63, 8, 40, 91, 66, 49, 94, 21],
[24, 55, 58, 5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72],
[21, 36, 23, 9, 75, 0, 76, 44, 20, 45, 35, 14, 0, 61, 33, 97, 34, 31, 33, 95],
[78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 3, 80, 4, 62, 16, 14, 9, 53, 56, 92],
[16, 39, 5, 42, 96, 35, 31, 47, 55, 58, 88, 24, 0, 17, 54, 24, 36, 29, 85, 57],
[86, 56, 0, 48, 35, 71, 89, 7, 5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58],
[19, 80, 81, 68, 5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 4, 89, 55, 40],
[4, 52, 8, 83, 97, 35, 99, 16, 7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66],
[88, 36, 68, 87, 57, 62, 20, 72, 3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69],
[4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 8, 46, 29, 32, 40, 62, 76, 36],
[20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74, 4, 36, 16],
[20, 73, 35, 29, 78, 31, 90, 1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57, 5, 54],
[1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 1, 89, 19, 67, 48]
]
Here is the code:
def largest_product_grid(grid):
greatest = 0
patterns = [
[(1, 0), (2, 0), (3, 0)],
[(1, -1), (2, -2), (3, -3)],
[(0, -1), (0, -2), (0, -3)],
[(0, 1), (0, 2), (0, 3)],
[(-1, -1), (-2, -2), (-3, -3)]]
for y in range(0, 19):
for x in range(0, 19):
for p in patterns:
product = grid[y][x] * grid[p[0][1]][p[0][0]] * grid[p[1][1]][p[1][0]] * grid[p[2][1]][p[2][0]]
if greatest < product:
greatest = product
return greatest
I'm pretty sure it's doing more calculations than it needs to, doing the same math several times and going further on both x and y than I probably need to go. Yet I still keep getting the wrong answer. The correct should be: 70600674.
Edit: Question:
"What is the greatest product of four adjacent numbers in the same
direction (up, down, left, right, or diagonally) in the 20×20 grid?"
I was expecting index out of range errors, yet I oversaw a stupid error.
For starters, you want your search pattern to be a function of x and y.
product = grid[y][x] * grid[p[0][1]][p[0][0]] * grid[p[1][1]][p[1][0]] * grid[p[2][1]][p[2][0]]
Right now, p[0][1] will always return the same value no matter what x and y are. You should replace the above line with something like:
product = grid[y][x] * grid[y + p[0][1]][x + p[0][0]] * grid[y + p[1][1]][x + p[1][0]] * grid[y + p[2][1]][x + p[2][0]]

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