I want to draw a circle in the console using characters instead of pixels, for this I need to know how many pixels are in each row. The diameter is given as input, you need to output a list with the width in pixels of each line of the picture
For example:
input: 7
output: [3, 5, 7, 7, 7, 5, 3]
input: 12
output: [4, 8, 10, 10, 12, 12, 12, 12, 10, 10, 8, 4]
How can this be implemented?
This was a good reminder for me to be careful when mixing zero-based and one-based computations. In this case, I had to account for the for loops being zero-based, but the quotient of the diameter divided by 2 being one-based. Otherwise, the plots would have been over or under by 1.
By the way, while I matched your answer for 7, I didn't come up with the same exact plot for 12:
NOTE - Tested using Python 3.9.6
pixels_in_line = 0
pixels_per_line = []
diameter = int(input('Enter the diameter of the circle: '))
# You must account for the loops being zero-based, but the quotient of the diameter / 2 being
# one-based. If you use the exact radius, you will be short one column and one row.
offset_radius = (diameter / 2) - 0.5
for i in range(diameter):
for j in range(diameter):
x = i - offset_radius
y = j - offset_radius
if x * x + y * y <= offset_radius * offset_radius + 1:
print('*', end=' ')
pixels_in_line += 1
else:
print(' ', end=' ')
pixels_per_line.append(pixels_in_line)
pixels_in_line = 0
print()
print('The pixels per line are {0}.'.format(pixels_per_line))
Output for 7:
Enter the diameter of the circle: 7
* * *
* * * * *
* * * * * * *
* * * * * * *
* * * * * * *
* * * * *
* * *
The pixels per line are [3, 5, 7, 7, 7, 5, 3].
Output for 12:
Enter the diameter of the circle: 12
* *
* * * * * *
* * * * * * * *
* * * * * * * * * *
* * * * * * * * * *
* * * * * * * * * * * *
* * * * * * * * * * * *
* * * * * * * * * *
* * * * * * * * * *
* * * * * * * *
* * * * * *
* *
The pixels per line are [2, 6, 8, 10, 10, 12, 12, 10, 10, 8, 6, 2].
if x * x + y * y <= offset_radius * offset_radius + 1: to use: if x ** 2 + y ** 2 <= offset_radius ** 2 + 1:. And by the way, you can put all * in one string (join the lines with '\n') and print the string in one step. Don't need to print every pixel and don't need to count every * inside the loop (they can be counted with list.count('*') method). I think it would be a more clean code, just three steps: (1) make the string, (2) print the string, (3) count the 'pixels' per lines in the string and pint the report. –
Frederik Based on Rob's solution (all credits to Rob!) I've managed to tweak the code for 12x12 pixel grid as well:
diameter = 12
radius = diameter / 2 - .5
r = (radius + .25)**2 + 1
result = ''
for i in range(diameter):
y = (i - radius)**2
for j in range(diameter):
x = (j - radius)**2
if x + y <= r:
result = result + '* '
else:
result = result + ' '
result = result + '\n'
print(result)
result = result.split('\n')[:-1]
pixels_per_line = [x.count('*') for x in result]
print(f'The pixels per line are {pixels_per_line}.')
Output:
* * * *
* * * * * * * *
* * * * * * * * * *
* * * * * * * * * *
* * * * * * * * * * * *
* * * * * * * * * * * *
* * * * * * * * * * * *
* * * * * * * * * * * *
* * * * * * * * * *
* * * * * * * * * *
* * * * * * * *
* * * *
The pixels per line are [4, 8, 10, 10, 12, 12, 12, 12, 10, 10, 8, 4].
If you need the empty area inside the circle it can be done with minimal changes:
diameter = 7
radius = diameter / 2 - .5
r = (radius + .25)**2 + 1
r_min = (radius - 1)**2 + 1 # <-------- here
result = ''
for i in range(diameter):
y = (i - radius)**2
for j in range(diameter):
x = (j - radius)**2
if r_min <= x + y <= r: # <----- here
result = result + '* '
else:
result = result + ' '
result = result + '\n'
print(result)
Output:
* * *
* * * *
* * * *
* *
* * * *
* * * *
* * *
* * * *
* * * * * *
* * * *
* *
* * * *
* *
* *
* * * *
* *
* * * *
* * * * * *
* * * *
you can do like this. This is based on the circle formula x^2 + y^2 is equal to radius and any point inside is less than radius.
import math
radius = 10
for i in range(-radius,radius+1):
for j in range(-radius, radius +1):
if radius-1 <= math.sqrt(i**2 + j**2) <= radius:
print("*",end = " ")
else:
print(" ", end = ' ')
print()
Output is as follows
*
* * * * * * * * *
* * * *
* *
* *
* *
* *
* *
* *
* *
* *
* *
* * * *
* *
* *
* *
* *
* *
* *
* *
* *
* *
* * * *
* * * * * * * * *
*
if you remove the greater than condition
radius = 12
for i in range(-radius,radius+1):
for j in range(-radius, radius +1):
if math.sqrt(i**2 + j**2) <= radius:
print("*",end = " ")
else:
print(" ", end = ' ')
print()
output
*
* * * * * * * * *
* * * * * * * * * * * * *
* * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * *
* * * * * * * * * * * * *
* * * * * * * * *
*
If you can do some math, you can use only one loop.
def calc_circle(diameter):
pixels_per_line = []
parity = diameter % 2
radius = (diameter / 2.)-0.5
for i in range(diameter):
j = abs(i-radius)
pixels_in_line = int((radius * radius - j*j+3)**(1/2)*2) # '+3' is an arbitrary number
pixels_per_line.append(pixels_in_line+int((pixels_in_line%2)^parity))
return pixels_per_line
The output is below:
calc_offset_circle(7)
> [3, 5, 7, 7, 7, 5, 3]
calc_offset_circle(12)
> [4, 8, 10, 10, 12, 12, 12, 12, 10, 10, 8, 4]
The draw function is as follows:
def print_circle(lines):
wh = len(lines)
result = ''
for i in range(wh):
for j in range(int((wh-lines[i])/2)): result = result + ' '
for j in range(lines[i]): result = result + '* '
for j in range(int((wh-lines[i])/2)): result = result + ' '
result = result + '\n'
print(result)
And the result is below:
print_circle(calc_offset_circle(7))
* * *
* * * * *
* * * * * * *
* * * * * * *
* * * * * * *
* * * * *
* * *
print_circle(calc_offset_circle(12))
* * * *
* * * * * * * *
* * * * * * * * * *
* * * * * * * * * *
* * * * * * * * * * * *
* * * * * * * * * * * *
* * * * * * * * * * * *
* * * * * * * * * * * *
* * * * * * * * * *
* * * * * * * * * *
* * * * * * * *
* * * *
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