def is_palindrome(input_string):
# We'll create two strings, to compare them
new_string = input_string.strip()
print(new_string)
# Traverse through each letter of the input string
newstringseperated = new_string.split()
n = len(new_string)
if n%2 == 0:
for i in range(n//2 - 1):
if newstringseperated[i] != newstringseperated[n-1-i]:
print("False")
hello = 1
if hello == 1:
print("False")
else:
print("True")
if (n%2) != 0:
for i in range((n-1)//2):
if newstringseperated[i] != newstringseperated[n-1-i]:
hello2 = 1
if hello2 == 1:
print("False")
else:
print("True")
I tried to execute this code on the words "kayak" and "deed".
It is showing index error for both of them. What is the problem here? Can someone help me find the mistake?
You have a number of problems here. As #John says, you want to use n // 2 - 1 rather than n / 2 - 1 so that the result is an integer. If you use re.sub() instead of split(), you can get rid of whitespace in the middle of your input strings and get rid of tabs as well as spaces. The big issue is that splitting the input string to create newstringseperated and using that is messing you up. If you instead operate on new_string directly, your code will work. Another small detail...you can break as soon as you recognize a mismatch. This version of your code does what I think you're expecting:
import re
def is_palindrome(input_string):
# We'll create two strings, to compare them
new_string = re.sub(r'\s+', '', input_string)
print(new_string)
# Traverse through each letter of the input string
# newstringseperated = new_string.split()
n = len(new_string)
if n % 2 == 0:
hello = 0
for i in range(n // 2 - 1):
if new_string[i] != new_string[n - 1 - i]:
hello = 1
break
if hello == 1:
print("False")
else:
print("True")
# Add any non-blank letters to the
# end of one string, and to the front
# of the other string.
if (n % 2) != 0:
hello2 = 0
for i in range((n - 1) // 2):
if new_string[i] != new_string[n - 1 - i]:
hello2 = 1
break
if hello2 == 1:
print("False")
else:
print("True")
is_palindrome("kayak")
is_palindrome("deed")
is_palindrome("abcde")
is_palindrome("abcd")
Result:
kayak
True
deed
True
abcde
False
abcd
False
It is better to not have the two cases (odd vs even lengths) in your code. Here's a way to have just one version of your inner logic:
import re
def is_palindrome(input_string):
new_string = re.sub(r'\s+', '', input_string)
print(new_string)
# Traverse through each letter of the input string
n = len(new_string)
for i in range(n // 2 - 1 + n % 2):
if new_string[i] != new_string[n - 1 - i]:
hello = 1
break
else:
hello = 0
print("False" if hello == 1 else "True")
This produces the same result.
Just reverse the string and test so no looping needed:
def is_palindrome(txt):
txt = txt.replace(' ', '')
return txt == txt[::-1]
First of all, to delete whitespaces, use replace() instead of strip() as it takes care of whitespaces in the middle of the string as well.
Secondly, the bigger problem is the split() method. It creates a list of substrings based on a specific separator and what you are essentially doing is comparing words instead of characters. Honestly, you don't even need this method to check for palindrome, just modifying the code a bit like this should work fine:
def is_palindrome(input_string):
new_string = input_string.replace(" ", "")
n = len(new_string)
for i in range(n // 2):
if new_string[i] != new_string[n - 1 - i]:
print("False")
return False
print("True")
return True
I had to do this on my phone but this should work if your looking for a palindrome:
txt = "hannah"
txt2 = "kayak"
txt3 = "blaat"
def palin(txt):
first_half = len(txt) // 2
start_second_half = first_half -1 if len(txt)%2==0 else first_half
return txt[:first_half] == txt[-1:start_second_half:-1]
print(palin(txt))
print(palin(txt2))
print(palin(txt3))
I'm looking for a code that runs, i.e:
int(input) = 2565
Printed Output should be like:
2 + 5 + 6 + 5 = 18 = 1 + 8 = 9
I wrote the code that gives final answer "9". But I couldn't managed to write it with every digit separated "+" sign. Assuming that I need to use while loop but how can I write the code so it will be like the output above?
You can use something like this:
def sum_of_digits(s):
if s < 10:
return s
return sum_of_digits(sum(int(c) for c in str(s)))
> sum_of_digits(2565)
9
It recursively checks if the numerical value is less than 10. If it does, it returns this value. If not, it adds the digits, then recursively calls itself on the result.
Edit
To print out the steps as it goes along, you could do something like this:
def sum_of_digits(s):
if s < 10:
print(s)
return s
print(' + '.join(c for c in str(s)) + ' = ')
return sum_of_digits(sum(int(c) for c in str(s)))
First, initiate an empty string output_str.
With a while loop which contniues when our integer is > 9:
[s for s in str(x)] would create a list of the digits (as strings) of our integer. It's called a list comprehension, is very useful, and my advice is to read a bit about it.
With " + ".join() we create a string with " + " between the
digits. Add this string at the end of output_str.
Add " = " to the end of output_str.
Calculate the sum of the digits (we cannot use sum(lst_of_digits) because it's a list of strings. sum([int(s) for s in lst_of_digits]) converts the string list into an inter list, which can be summed using sum()). Store the sum into x.
Add the new x + " = " to output_string.
At the end of the string, we have a redundant " = " (because the last (5) was not needed), let's just remove the last 3 chars (=) from it.
x = 2565
output_str = ""
while x > 9:
lst_of_digits = [s for s in str(x)]
output_str += " + ".join(lst_of_digits)
output_str += " = "
x = sum([int(s) for s in lst_of_digits])
output_str += f"{x} = "
output_str = output_str[:-3]
outputs:
output_str = '2 + 5 + 6 + 5 = 18 = 1 + 8 = 9'
You can play around with the end keyword argument of the print function which is the last character/string that print will put after all of its arguments are, well, printed, by default is "\n" but it can be change to your desire.
And the .join method from string which put the given string between the given list/iterable of strings to get the desire result:
>>> " + ".join("123")
'1 + 2 + 3'
>>>
Mixing it all together:
def sum_digit(n):
s = sum(map(int,str(n)))
print(" + ".join(str(n)),"=",s, end="")
if s<10:
print()
return s
else:
print(" = ",end="")
return sum_digit(s)
Here we first get the sum of the digit on s, and print it as desire, with end="" print will not go to the next line which is necessary for the recursive step, then we check if done, and in that case print a new empty line if not we print an additional = to tie it for the next recursive step
>>> sum_digit(2565)
2 + 5 + 6 + 5 = 18 = 1 + 8 = 9
9
>>>
This can be easily be modify to just return the accumulated string by adding an extra argument or to be iterative but I leave those as exercise for the reader :)
I am a noob but this should do what you want.
Cheers,
Guglielmo
import math
import sys
def sumdigits(number):
digits = []
for i in range( int(math.log10(number)) + 1):
digits.append(int(number%10))
number = number/10
digits.reverse()
string = ''
thesum = 0
for i,x in enumerate(digits):
string += str(x)
thesum += x
if i != len(digits)-1: string += ' + '
else: string += ' = '
if thesum > 10:
return string,thesum,int(math.log10(number))+1
else:
return string,thesum,0
def main():
number = float(sys.argv[1])
finalstring = ''
string,thesum,order = sumdigits(number)
finalstring += string
finalstring += str(thesum)
while order > 0:
finalstring += ' = '
string,thesum,order = sumdigits(thesum)
finalstring += string
finalstring += str(thesum)
print 'myinput = ',int(number)
print 'Output = ',finalstring
if __name__ == "__main__":
main()
My goal is to write a function which change every even letter into upper letter and odd to lower (space also count as a one element).
This is my code
def to_weird_case(s):
for i in s:
if len(i) % 2 == 0:
s[i] = i.upper() + s(i+1)
else:
s[i] = i.lower() + s(i+2)
return i
I think it should be quite correct, but it gives me error.
line 7, in to_weird_case
s[i] = i.lower() + s(str(i)+2)
TypeError: must be str, not int
EDIT:
I have a sugesstion but I don't know how to make it. I try it for myself and back here.
This needs to definitly explicietly state that the zero indexing uppercase is for each word.
Do you know guys how to make it?
So we can analyze your code and just explain what you typed:
def to_weird_case(s):
for i in s: # s is your string, and i is the actual character
if len(i) % 2 == 0: # if your length of the character can be divided by 2. Hmm this is weird
s[i] = i.upper() + s(i+1) # s[i] change a character in the string but you should provide an index (i) so an integer and not a character. But this is not supported in Python.
else:
s[i] = i.lower() + s(i+2)
return i # This will exit after first iteraction, so to_weird_case("this") will return "t".
So what you need to is first create a output string and fill that. And when iteration over s, you want the index of the char and the char value itself.
def to_weird_case(s):
output = ""
for i, myChar in enumerate(s):
if i % 2 == 0:
output += myChar.upper()
else:
output += myChar.lower()
return output
my_sentence = "abcdef"
print(to_weird_case(my_sentence))
And when you want to ignore spaces, you need to keep track of actual characters (excluding spaces)
def to_weird_case(s):
output = ""
count = 0
for myChar in s:
if myChar.isspace():
output += myChar
else:
if count % 2 == 0:
output += myChar.upper()
else:
output += myChar.lower()
count += 1
return output
my_sentence = "abc def"
print(to_weird_case(my_sentence))
Test this yourself
def to_weird_case(s):
for i in s:
print (i)
After doing this you will find that i gives you characters.
if len(i) % 2 == 0:
This line is incorrect as you are trying to find the length of a single character. len(s) would be much better.
So the code will be like
def to_weird_case(s):
s2 = "" #We create another string as strings are immutable in python
for i in range(len(s)):
if i % 2 == 0:
s2 = s2 + s[i].upper()
else:
s2 = s2 + s[i].lower()
return s2
From #RvdK analysis, you'ld have seen where corrections are needed. In addition to what has been pointed out, I want you to note that s[i] will work fine only if i is an integer, but in your case where (by assumption) i is a string you'll encounter several TypeErrors. From my understanding of what you want to do, it should go this way:
def to_weird_case(s):
for i in s:
if s.index(i) % 2 == 0:
s[s.index(i)] = i.upper() + s[s.index(i)]
elif s.index(i) % 2 == 1:
s[s.index(i)] = i.lower() + s[s.index(i)]
return i # or possibly return s
It is possible to do in a single line using a list comprehension
def funny_case(s):
return "".join([c.upper() if idx%2==0 else c.lower() for idx,c in enumerate(s)])
If you want to treat each word separately then you can split it up in to a list of words and "funny case" each word individually, see below code
original = "hello world"
def funny_case(s):
return "".join([c.upper() if idx%2==0 else c.lower() for idx,c in enumerate(s) ])
def funny_case_by_word(s):
return " ".join((funny_case(word) for word in s.split()))
print(funny_case_by_word(original))
Corrected code is as follows
def case(s):
txt=''
for i in range(len(s)):
if i%2==0:
txt+=s[i].upper()
else:
txt+=s[i].lower()
return txt
String assignment gives error in Python therefore i recommend considering my approach
When looping over elements of s, you get the letter itself, not its index. You can use enumerate to get both index and letter.
def to_weird_case(s):
result = ''
for index, letter in enumerate(s):
if index % 2 == 0:
result += letter.upper()
else:
result += letter.lower()
return result
correct code:
def to_weird_case(s):
str2 = ""
s.split() # through splitting string is converted to list as it is easy to traverse through list
for i in range(0,len(s)):
n = s[i] # storing value in n
if(i % 2 == 0):
str2 = str2 + n.upper()
else:
str2 = str2 + n.lower()
return str2
str1 = "hello world"
r = to_weird_case(str1)
print(r)
I am working through the book "Introduction to Computation and Programming Using Python" by Dr. Guttag. I am working on the finger exercises for Chapter 3. I am stuck. It is section 3.2, page 25. The exercise is: Let s be a string that contains a sequence of decimal numbers separated by commas, e.g., s = '1.23,2.4,3.123'. Write a program that prints the sume of the numbers in s.
The previous example was:
total = 0
for c in '123456789':
total += int(c)
print total.
I've tried and tried but keep getting various errors. Here's my latest attempt.
total = 0
s = '1.23,2.4,3.123'
print s
float(s)
for c in s:
total += c
print c
print total
print 'The total should be ', 1.23+2.4+3.123
I get ValueError: invalid literal for float(): 1.23,2.4,3.123.
Floating point values cannot have a comma. You are passing 1.23,2.4,3.123 as it is to float function, which is not valid. First split the string based on comma,
s = "1.23,2.4,3.123"
print s.split(",") # ['1.23', '2.4', '3.123']
Then convert each and and every element of that list to float and add them together to get the result. To feel the power of Python, this particular problem can be solved in the following ways.
You can find the total, like this
s = "1.23,2.4,3.123"
total = sum(map(float, s.split(",")))
If the number of elements is going to be too large, you can use a generator expression, like this
total = sum(float(item) for item in s.split(","))
All these versions will produce the same result as
total, s = 0, "1.23,2.4,3.123"
for current_number in s.split(","):
total += float(current_number)
Since you are starting with Python, you could try this simple approach:
Use the split(c) function, where c is a delimiter. With this you will have a list numbers (in the code below). Then you can iterate over each element of that list, casting each number to a float (because elements of numbers are strings) and sum them:
numbers = s.split(',')
sum = 0
for e in numbers:
sum += float(e)
print sum
Output:
6.753
From the book Introduction to Computation and Programming using Python at page 25.
"Let s be a string that contains a sequence of decimal numbers separated by commas, e.g., s
= '1.23,2.4,3.123'. Write a program that prints the sum of the numbers in s."
If we use only what has been taught so far, then this code is one approach:
tmp = ''
num = 0
print('Enter a string of decimal numbers separated by comma:')
s = input('Enter the string: ')
for ch in s:
if ch != ',':
tmp = tmp + ch
elif ch == ',':
num = num + float(tmp)
tmp = ''
# Also include last float number in sum and show result
print('The sum of all numbers is:', num + float(tmp))
total = 0
s = '1.23,2.4,3.123'
for c in s.split(','):
total = total + float(c)
print(total)
Works Like A Charm
Only used what i have learned yet
s = raw_input('Enter a string that contains a sequence of decimal ' +
'numbers separated by commas, e.g. 1.23,2.4,3.123: ')
s = "," + s+ ","
total =0
for i in range(0,len(s)):
if s[i] == ",":
for j in range(1,(len(s)-i)):
if s[i+j] == ","
total = total + float(s[(i+1):(i+j)])
break
print total
This is what I came up with:
s = raw_input('Enter a sequence of decimal numbers separated by commas: ')
aux = ''
total = 0
for c in s:
aux = aux + c
if c == ',':
total = total + float(aux[0:len(aux)-1])
aux = ''
total = total + float(aux) ##Uses last value stored in aux
print 'The sum of the numbers entered is ', total
I think they've revised this textbook since this question was asked (and some of the other's have answered.) I have the second edition of the text and the split example is not on page 25. There's nothing prior to this lesson that shows you how to use split.
I wound up finding a different way of doing it using regular expressions. Here's my code:
# Intro to Python
# Chapter 3.2
# Finger Exercises
# Write a program that totals a sequence of decimal numbers
import re
total = 0 # initialize the running total
for s in re.findall(r'\d+\.\d+','1.23, 2.2, 5.4, 11.32, 18.1,22.1,19.0'):
total = total + float(s)
print(total)
I've never considered myself dense when it comes to learning new things, but I'm having a hard time with (most of) the finger exercises in this book so far.
s = input('Enter a sequence of decimal numbers separated by commas: ')
x = ''
sum = 0.0
for c in s:
if c != ',':
x = x + c
else:
sum = sum + float(x)
x = ''
sum = sum + float(x)
print(sum)
This is using just the ideas already covered in the book at this point. Basically it goes through each character in the original string, s, using string addition to add each one to the next to build a new string, x, until it encounters a comma, at which point it changes what it has as x to a float and adds it to the sum variable, which started at zero. It then resets x back to an empty string and repeats until all the characters in s have been covered
Here's a solution without using split:
s='1.23,2.4,3.123,5.45343'
pos=[0]
total=0
for i in range(0,len(s)):
if s[i]==',':
pos.append(len(s[0:i]))
pos.append(len(s))
for j in range(len(pos)-1):
if j==0:
num=float(s[pos[j]:pos[j+1]])
total=total+num
else:
num=float(s[pos[j]+1:pos[j+1]])
total=total+num
print total
My way works:
s = '1.23, 211.3'
total = 0
for x in s:
for i in x:
if i != ',' and i != ' ' and i != '.':
total = total + int(i)
print total
My answer is here:
s = '1.23,2.4,3.123'
sum = 0
is_int_part = True
n = 0
for c in s:
if c == '.':
is_int_part = False
elif c == ',':
if is_int_part == True:
total += sum
else:
total += sum/10.0**n
sum = 0
is_int_part = True
n = 0
else:
sum *= 10
sum += int(c)
if is_int_part == False:
n += 1
if is_int_part == True:
total += sum
else:
total += sum/10.0**n
print total
I have managed to answer the question with the knowledge gained up until 3.2 the section for loop
s = '1.0, 1.1, 1.2'
print 'List of decimal number'
print s
total = 0.0
for c in s:
if c == ',':
total += float(s[0:(s.index(','))])
d = int(s.index(','))+1
s = s[(d+1) : len(s)]
s = float(s)
total += s
print '1.0 + 1.1 + 1.2 = ', total
This is the answer to the question i feel that the split function is not good for beginner like you and me.
Considering the fact that you might not yet be exposed to more complex functions, simply try these out.
total = 0
for c in "1.23","2.4",3.123":
total += float(c)
print total
My answer:
s = '2.1,2.0'
countI = 0
countF = 0
totalS = 0
for num in s:
if num == ',' or (countF + 1 == len(s)):
totalS += float(s[countI:countF])
if countF < len(s):
countI = countF + 1
countF += 1
print(totalS) # 4.1
This only works if the numbers are floats
Here is my answer. It is similar to the one by user5716300 above, but since I am also a beginner I explicitly created a separate variable s1 for the split string:
s = "1.23,2.4,3.123"
s1 = s.split(",") #this creates a list of strings
count = 0.0
for i in s1:
count = count + float(i)
print(count)
If we are just sticking with the content for that chapter, I came up with this: (though using that sum method mentioned by theFourthEye is also pretty slick):
s = '1.23,3.4,4.5'
result = s.split(',')
result = list(map(float, result))
n = 0
add = 0
for a in result:
add = add + result[n]
n = n + 1
print(add)
I just wanna to post my answer because I am reading this book now.
s = '1.23,2.4,3.123'
ans = 0.0
i = 0
j = 0
for c in s:
if c == ',':
ans += float(s[i:j])
i = j + 1
j += 1
ans += float(s[i:j])
print(str(ans))
Using knowledge from the book:
s = '4.58,2.399,3.1456,7.655,9.343'
total = 0
index = 0
for string in s:
index += 1
if string == ',':
temp = float(s[:index-1])
s = s[index:]
index = 0
total += temp
temp = 0
print(total)
Here I used string slicing, and by slicing the original string every time our 'string' variable is equal to ','. Also using an index variable to keep track of the number that is before the comma. After slicing the string, the number that gets input into tmp is cleared with the comma in front of it, the string becoming another string without that number.
Because of this, the index variable needs to be reset every time this happens.
Here's mine using the exact string in the question and only what has been taught so far.
total = 0
temp_num = ''
for char in '1.23,2.4,3.123':
if char == ',':
total += float(temp_num)
temp_num = ''
else:
temp_num += char
total += float(temp_num) #to catch the last number that has no comma after it
print(total)
I know this isn't covered in the book up to this point but I happened to learn the use of the eval() function on my own prior to getting to this question and used it to solve.
total = 0
s = "1.23,2.4,3.123"
x = eval(s)
y = sum(x)
print(y)
I think this is the easiest way to answer the question. It uses the split command, which is not introduced in the book at this moment but a very useful command.
s = input('Insert string of decimals, e,g, 1.4,5.55,12.651:')
sList = s.split(',') #create a list of these values
print(sList) #to check if list is correctly created
total = 0 #for creating the variable
for each in sList:
total = total + float(each)
print(total)
total =0
s = {1.23,2.4,3.123}
for c in s:
total = total+float(c)
print(total)