Tag: python

I have a text file something like,

3 forwhomthebelltolls
-6 verycomplexnumber

The question is, if the integer K is positive, take the first K characters and put them at the end of the string. If it’s negative, take the last K characters and put them at the front of the string. Like this:

whomthebelltollsfor
numberverycomplex

My code is

file = open("tex.txt","r")

for line in file:
    K, sentence = int(line.split(" ")[0]), line.split(" ")[1]
    new_sentence = sentence[K:] + sentence[:K]
    print(new_sentence)

however it prints the values like:

whomthebelltolls
for
numberverycomplex

I do not understand why this happens. I am just adding two strings however in printing part the second part that I add goes down.

Solution:

The actual contents of the file:

3 forwhomthebelltolls\n
-6 verycomplexnumber

When you iterate through the file with for line in file, you’re taking the entire line, including the newline character at the end. You’re never removing that. And so, sentence[K:] resolves to whomthebelltolls\n, and sentence[:k] resolves to for. The entire string is whomthebelltolls\nfor. Since there’s a newline in the middle of the string, that gets printed.

To fix this, strip the string first:

for line in file:
    K, sentence = int(line.split(" ")[0]), line.split(" ")[1].strip()
    ...

I’m trying to figure out how to reverse a string using Python without using the [::-1] solution.

My code seems to work fine for several test cases, but it adds an extra space for one instance and I can’t figure out why.

def reverse(s):
    r = list(s)
    start, end = 0, len(s) - 1
    x = end//2
    for i in range(x):
        r[start], r[end] = r[end], r[start]
        start += 1
        end -= 1

    print(''.join(r))


reverse('A man, a plan, a canal: Panama')

# returns 'amanaP :lanac  a,nalp a ,nam A'
# note the double space ^^ - don't know why


reverse('a monkey named fred, had a banana')

# 'returns ananab a dah ,derf deman yeknom a'


reverse('Able was I ere I saw Elba')

# returns 'ablE was I ere I saw elbA'

Solution:

Change

    x = end//2

to

    x = len(s)//2

I’m trying to make a little program to learn more, but am stuck when it comes to using random.

Here is an example of what im going off of https://trinket.io/python/3338c95430

I’ve tried using random.randrange, random.choice, random.random with everything for them and it sends an error code saying random doesnt have a function of randrange, choice, or random.

import turtle, math, random, time

wn = turtle.Screen()
wn.bgcolor('grey')
Rocket = turtle.Turtle()
Rocket.speed(0)
Rocket.color('red') ## this is what i want to randomize
rotate=int(90)

def drawCircles(t,size):
    for i in range(15):
        t.circle(size)
        size=size-10
def drawSpecial(t,size,repeat):
    for i in range(repeat):
        drawCircles(t,size)
        t.right(360/repeat)
drawSpecial(Rocket,100,10)

Eventually i would like to implement more randomized processes like the size and placement but for now im just focusing on color.

Solution:

Without using additional imports it’s fairly simple:

turtle.colormode(255) # sets the color mode to RGB

R = random.randrange(0, 256, 100) # last value optional (step) 
B = random.randrange(0, 256)
G = random.randrange(0, 256)

# using step allows more control if needed
# for example the value of `100` would return `0`, `100` or `200` only

Rocket.color(R, G, B) ## randomized from values above

Using randomized values of (200,255,23):

_{EDIT: Regarding “would i just change the turtle.colormode()
to Rocket.colormode() for the next one?”}

The way I would recommend doing it would be to create a function:

def drawColor():

    turtle.colormode(255)

    R = random.randrange(0, 256)
    B = random.randrange(0, 256)
    G = random.randrange(0, 256)

    return R, G, B

Rocket.color(drawColor())

This way you can call drawColor() anytime you want a new color.

Now that you have the basics of randomizing colors for your drawing you can get quite creative with the values for some awesome looking results (adjust integers to your liking):

#!/usr/bin/python

import turtle, math, random, time

def drawColor(a, b, o):
    turtle.colormode(255)
    R = random.randrange(a, b, o) # last value is step (optional)
    B = random.randrange(a, b, o)
    G = random.randrange(a, b, o)
    # print(R, G, B)
    return R, G, B

def drawRocket(offset):
    Rocket = turtle.Turtle()
    Rocket.speed(0)
    Rocket.color(drawColor(20, 100, 1)) ## this is what i want to randomize
    rotate=int(random.randrange(90))
    drawSpecial(Rocket,random.randrange(0, 10), offset)

def drawCircles(t,size):
    for i in range(30):
        t.circle(size)
        size = size-20

def drawSpecial(t,size,repeat):
    for i in range(repeat):
        drawCircles(t,size)
        t.right(360/repeat)

def drawMain(x, y):
    wn = turtle.Screen()
    wn.bgcolor(drawColor(0, 20, 2))

    for i in range(3):
        drawRocket(x)
        x+=y
        # print(x)

drawMain(2, 10)
input("Press ENTER to exit")