I would like to convert every other letter of a string into uppercase. For example provided the input is 'ahdjeryu', the result should be 'AhDjErYu'.
I was trying this:
def mycode(letters):
myword = letters.split()
for i in letters:
if i%2 == 0:
return i.upper()
else:
return i.lower()
print(mycode('ahdjeryu'))
The error thrown as:
if i%2==0:
TypeError: not all arguments converted during string formatting
Several issues with your code:
You only need to use str.split to remove whitespace. Here, not necessary.
To extract the index of a letter as well as the letter, use enumerate.
return will return just one letter. You can instead yield letters and then use str.join on the generator.
Here's a working example:
def mycode(letters):
for idx, i in enumerate(letters):
if idx % 2 == 0:
yield i.upper()
else:
yield i.lower()
print(''.join(mycode('ahdjeryu')))
AhDjErYu
The above logic can be equivalently implemented via a generator comprehension:
res = ''.join(i.upper() if idx % 2 == 0 else i.lower() for idx, i in enumerate(letters))
Your i is a string of one character, not an index. So you can't do i%2. Use enumerate to get both the index and the value.
alternating = ''.join(letter.upper() if index%2==0 else letter.lower() for index, letter in enumerate(text)
Yes, it error, cause i now is letter not a number, so it can't mod for 2.
Im not sure syntax about looping by for in Python but may you can try:
cnt = 0
for i in letters:
if cnt%2 == 0:
return i.upper()
else:
return i.lower()
cnt++
Hope it can help you!
Fix me if I have any wrong. Thanks
#Abhi, this is inline with your original logic. You need r to get the index of the letters in the string.
def mycode(letters):
for ch in letters:
r=letters.index(ch)
if r%2 == 0:
letters=letters.replace(ch,letters[r].upper())
else:
letters=letters.replace(ch,letters[r].lower())
return letters
print(mycode('ahdjeryu'))
Related
I'm trying to solve this exercise using enumerate, but I don't have any idea how to implement the value. In a mathematical way I said if for index and index+1 letter is the same do nothing, if the upcoming letter is different write letter. But I have no idea how to do it in python
Desired result aaabbbaas => abas.
def zad6(string):
b =""
for index,letter in enumerate(string):
if letter[index] == letter[index+1]:
b += None
else:
b += letter
return b
print(zad6("aaabbbaas"))
Here is a fix of your code using enumerate, you can check if each previous letter was the same, except the first time (index == 0):
def zad6(string):
for index, letter in enumerate(string):
if index == 0:
b = letter
elif letter != string[index-1]:
b += letter
return b
print(zad6("Baabba"))
output: 'Baba'
NB. this considers case, 'B' and 'b' will be different, if you want to ignore case use letter.lower() != string[index-1].lower()
alternative
just for the sake of showing an efficient solution, in real life you could use itertools.groupby:
from itertools import groupby
string = "Baabba"
''.join(l for l,_ in groupby(string))
Only append when you have something to append, there's no need to append None (and in fact, it doesn't work). Also, you should check if there's a next character at all in the string, or it will fail at the last iteration
def zad6(string):
b = ""
for index,letter in enumerate(string):
if index == len(string)-1 or letter != string[index+1]:
b+=letter
return b
print(zad6("Baabba"))
Here's an alternate approach without using a for loop, that seems a bit simpler:
from operator import itemgetter
def zad6(string):
filt = filter(lambda x: x[1] != string[x[0] - 1], enumerate(string))
return ''.join(map(itemgetter(1), filt))
assert zad6('aaabbbaas') == 'abas'
assert zad6('Baabba') == 'Baba'
So I'm a little confused as far as putting this small code together. My teacher gave me this info:
Iterate over the string and remove any triplicated letters (e.g.
"byeee mmmy friiiennd" becomes "bye my friennd"). You may assume any
immediate following same letters are a triplicate.
I've mostly only seen examples for duplicates, so how do I remove triplicates? My code doesn't return anything when I run it.
def removeTriplicateLetters(i):
result = ''
for i in result:
if i not in result:
result.append(i)
return result
def main():
print(removeTriplicateLetters('byeee mmmy friiiennd'))
main()
I have generalized the scenario with "n". In your case, you can pass n=3 as below
def remove_n_plicates(input_string, n):
i=0
final_string = ''
if not input_string:
return final_string
while(True):
final_string += input_string[i]
if input_string[i:i+n] == input_string[i]*n:
i += n
else:
i += 1
if i >= len(input_string):
break
return final_string
input_string = "byeee mmmy friiiennd"
output_string = remove_n_plicates(input_string, 3)
print(output_string)
# bye my friennd
You can use this for any "n" value now (where n > 0 and n < length of input string)
Your code returns an empty string because that's exactly what you coded:
result = ''
for i in result:
...
return result
Since result is an empty string, you don't enter the loop at all.
If you did enter the loop you couldn't return anything:
for i in result:
if i not in result:
The if makes no sense: to get to that statement, i must be in result
Instead, do as #newbie showed you. Iterate through the string, looking at a 3-character slice. If the slice is equal to 3 copies of the first character, then you've identified a triplet.
if input_string[i:i+n] == input_string[i]*n:
Without going in to writing the code to resolve the problem.
When you iterate over the string, add that iteration to a new string.
If the next iteration is the same as the previous iteration then do not add that to the new string.
This will catch both the triple and the double characters in your problem.
Tweaked a previous answer to remove a few lines that were not needed.
def remove_n_plicates(input_string, n):
i=0
result = ''
while(True):
result += input_string[i]
if input_string[i:i+n] == input_string[i]*n:
i += n
else:
i += 1
if i >= len(input_string):
break
return result
input_string = "byeee mmmy friiiennd"
output_string = remove_n_plicates(input_string, 3)
print(output_string)
# bye my friennd
Here's a fun way using itertools.groupby:
def removeTriplicateLetters(s):
return ''.join(k*(l//3+l%3) for k,l in ((k,len(list(g))) for k, g in groupby(s)))
>>> removeTriplicateLetters('byeee mmmy friiiennd')
'bye my friennd'
just modifying #newbie solution and using stack data structure as solution
def remove_n_plicates(input_string, n):
if input_string =='' or n<1:
return None
w = ''
c = 0
if input_string!='':
tmp =[]
for i in range(len(input_string)):
if c==n:
w+=str(tmp[-1])
tmp=[]
c =0
if tmp==[]:
tmp.append(input_string[i])
c = 1
else:
if input_string[i]==tmp[-1]:
tmp.append(input_string[i])
c+=1
elif input_string[i]!=tmp[-1]:
w+=str(''.join(tmp))
tmp=[input_string[i]]
c = 1
w+=''.join(tmp)
return w
input_string = "byeee mmmy friiiennd nnnn"
output_string = remove_n_plicates(input_string, 3)
print(output_string)
output
bye my friennd nn
so this is a bit dirty but it's short and works
def removeTriplicateLetters(i):
result,string = i[:2],i[2:]
for k in string:
if result[-1]==k and result[-2]==k:
result=result[:-1]
else:
result+=k
return result
print(removeTriplicateLetters('byeee mmmy friiiennd'))
bye my friennd
You have already got a working solution. But here, I come with another way to achieve your goal.
def removeTriplicateLetters(sentence):
"""
:param sentence: The sentence to transform.
:param words: The words in the sentence.
:param new_words: The list of the final words of the new sentence.
"""
words = sentence.split(" ") # split the sentence into words
new_words = []
for word in words: # loop through words of the sentence
new_word = []
for char in word: # loop through characters in a word
position = word.index(char)
if word.count(char) >= 3:
new_word = [i for i in word if i != char]
new_word.insert(position, char)
new_words.append(''.join(new_word))
return ' '.join(new_words)
def main():
print(removeTriplicateLetters('byeee mmmy friiiennd'))
main()
Output: bye my friennd
I'm trying to make a function that takes in a string from a user and then outputs the same string. However for each letter in an even position it outputs the corresponding lower case letter, and for each letter in an odd position it outputs the corresponding uppercase letter. Keep in mind only one word will be passed through it at a time.
I've tried to create a for loop with an if statement nested within it, but so far, the for loop stops after iterating through the first letter. My code is below:
def converter(string):
for letters in string:
if len(letters) % 2 == 0:
return letters.lower()
elif len(letters)% 2 != 0:
return letters.upper()
When I run the code:
converter('app')
The output I get is 'A'
The expected output should be 'aPp'
The first thing you need to know is that in Python, strings are immutable. So "modifying" a string means you have to build a new string from scratch in (here, I call that newstring).
Second, you are misunderstanding the loop. You are saying for letters in string. This loop iterates over each letter of the string. On the first iteration, letters is the first letter of the strong. You then convert it to upper case (since the length of a single letter is always 1), and return it. You aren't reaching the rest of the letters! In the code below, I change the plurality to just letter to make this idea clear.
This amends all of those problems:
def converter(string):
newstring = ""
for i, letter in enumerate(string):
if i % 2 == 0:
newstring += letter.lower()
elif i % 2 != 0:
newstring += letter.upper()
return newstring
This can be boiled down to a nice list comprehension:
def converter(string):
return "".join([letter.lower() if i % 2 == 0 else letter.upper()
for i, letter in enumerate(string)])
In [1]: def converter(string):
...: return ''.join([j.upper() if i % 2 == 1 else j.lower() for i, j in enumerate(string)])
In [2]: converter('apple')
Out[2]: 'aPpLe'
''.join([s.lower() if c % 2 == 0 else s.upper() for c, s in enumerate('apple')])
# returns 'aPpLe'
first check for the condition, then iterate through the string using the nice old enumerate built-in.
I'm trying to write a function which given a string returns another string that flips its lowercase characters to uppercase and viceversa.
My current aproach is as follows:
def swap_case(s):
word = []
for char in s:
word.append(char)
for char in word:
if char.islower():
char.upper()
else:
char.lower()
str1 = ''.join(word)
However the string doesn't actually change, how should I alter the characters inside the loop to do so?
PS: I know s.swapcase() would easily solve this, but I want to alter the characters inside the string during a for loop.
def swap_case(s):
swapped = []
for char in s:
if char.islower():
swapped.append(char.upper())
elif char.isupper():
swapped.append(char.lower())
else:
swapped.append(char)
return ''.join(swapped)
you can use swapcase.
string.swapcase(s)
Return a copy of s, but with lower case letters converted to upper case and vice versa.
Source : Python docs
>>> name = 'Mr.Ed' or name= ["M","r",".","E","d"]
>>> ''.join(c.lower() if c.isupper() else c.upper() for c in name)
'mR.eD'
Your code is not working because you are not storing the chars after transforming them. You created a list with all chars and then, you access the values without actually saving them. Also, you should make your function return str1 or you will never get a result. Here's a workaround:
def swap_case(s):
word = []
for char in s:
if char.islower():
word.append(char.upper())
else:
word.append(char.lower())
str1 = ''.join(word)
return str1
By the way, I know you want to do it with a for loop, but you should know there are better ways to perform this which would be more pythonic.
You can use this code:
s = "yourString"
res = s.swapcase()
print(res)
Which will output:
YOURsTRING
def swap_case(s):
x = ''
for i in s:
if i.isupper():
i = i.lower()
else:
i = i.upper()
x += ''.join(i)
return x
This question already has answers here:
How can I invert (swap) the case of each letter in a string?
(8 answers)
How can I use `return` to get back multiple values from a loop? Can I put them in a list?
(2 answers)
Closed 6 months ago.
I would like to change the chars of a string from lowercase to uppercase.
My code is below, the output I get with my code is a; could you please tell me where I am wrong and explain why?
Thanks in advance
test = "AltERNating"
def to_alternating_case(string):
words = list(string)
for word in words:
if word.isupper() == True:
return word.lower()
else:
return word.upper()
print to_alternating_case(test)
If you want to invert the case of that string, try this:
>>> 'AltERNating'.swapcase()
'aLTernATING'
There are two answers to this: an easy one and a hard one.
The easy one
Python has a built in function to do that, i dont exactly remember what it is, but something along the lines of
string.swapcase()
The hard one
You define your own function. The way you made your function is wrong, because
iterating over a string will return it letter by letter, and you just return the first letter instead of continuing the iteration.
def to_alternating_case(string):
temp = ""
for character in string:
if character.isupper() == True:
temp += character.lower()
else:
temp += word.upper()
return temp
Your loop iterates over the characters in the input string. It then returns from the very first iteration. Thus, you always get a 1-char return value.
test = "AltERNating"
def to_alternating_case(string):
words = list(string)
rval = ''
for c in words:
if word.isupper():
rval += c.lower()
else:
rval += c.upper()
return rval
print to_alternating_case(test)
That's because your function returns the first character only. I mean return keyword breaks your for loop.
Also, note that is unnecessary to convert the string into a list by running words = list(string) because you can iterate over a string just as you did with the list.
If you're looking for an algorithmic solution instead of the swapcase() then modify your method this way instead:
test = "AltERNating"
def to_alternating_case(string):
res = ""
for word in string:
if word.isupper() == True:
res = res + word.lower()
else:
res = res + word.upper()
return res
print to_alternating_case(test)
You are returning the first alphabet after looping over the word alternating which is not what you are expecting. There are some suggestions to directly loop over the string rather than converting it to a list, and expression if <variable-name> == True can be directly simplified to if <variable-name>. Answer with modifications as follows:
test = "AltERNating"
def to_alternating_case(string):
result = ''
for word in string:
if word.isupper():
result += word.lower()
else:
result += word.upper()
return result
print to_alternating_case(test)
OR using list comprehension :
def to_alternating_case(string):
result =[word.lower() if word.isupper() else word.upper() for word in string]
return ''.join(result)
OR using map, lambda:
def to_alternating_case(string):
result = map(lambda word:word.lower() if word.isupper() else word.upper(), string)
return ''.join(result)
You should do that like this:
test = "AltERNating"
def to_alternating_case(string):
words = list(string)
newstring = ""
if word.isupper():
newstring += word.lower()
else:
newstring += word.upper()
return alternative
print to_alternating_case(test)
def myfunc(string):
i=0
newstring=''
for x in string:
if i%2==0:
newstring=newstring+x.lower()
else:
newstring=newstring+x.upper()
i+=1
return newstring
contents='abcdefgasdfadfasdf'
temp=''
ss=list(contents)
for item in range(len(ss)):
if item%2==0:
temp+=ss[item].lower()
else:
temp+=ss[item].upper()
print(temp)
you can add this code inside a function also and in place of print use the return key
string=input("enter string:")
temp=''
ss=list(string)
for item in range(len(ss)):
if item%2==0:
temp+=ss[item].lower()
else:
temp+=ss[item].upper()
print(temp)
Here is a short form of the hard way:
alt_case = lambda s : ''.join([c.upper() if c.islower() else c.lower() for c in s])
print(alt_case('AltERNating'))
As I was looking for a solution making a all upper or all lower string alternating case, here is a solution to this problem:
alt_case = lambda s : ''.join([c.upper() if i%2 == 0 else c.lower() for i, c in enumerate(s)])
print(alt_case('alternating'))
You could use swapcase() method
string_name.swapcase()
or you could be a little bit fancy and use list comprehension
string = "thE big BROWN FoX JuMPeD oVEr thE LAZY Dog"
y = "".join([val.upper() if val.islower() else val.lower() for val in string])
print(y)
>>> 'THe BIG brown fOx jUmpEd OveR THe lazy dOG'
This doesn't use any 'pythonic' methods and gives the answer in a basic logical format using ASCII :
sentence = 'aWESOME is cODING'
words = sentence.split(' ')
sentence = ' '.join(reversed(words))
ans =''
for s in sentence:
if ord(s) >= 97 and ord(s) <= 122:
ans = ans + chr(ord(s) - 32)
elif ord(s) >= 65 and ord(s) <= 90 :
ans = ans + chr(ord(s) + 32)
else :
ans += ' '
print(ans)
So, the output will be : Coding IS Awesome