I want to find if two strings are anagrams or not..
I thought to sort them,and then check one by one but is there any algorithms for sorting stings? or another idea to make it? (simple ideas or code because i am a beginner )thanks
Strings are lists of characters in Haskell, so the standard sort simply works.
> import Data.List
> sort "hello"
"ehllo"
Your idea of sorting and then comparing sounds fine for checking anagrams.
I can give you and idea-(as I am not that much acquainted with haskell).
Take an array having 26 spaces.
Now for each character in the first string you increase certaing position in array.
If array A[26]={0,0,...0}
Now if you find 'a' then put A[1]=A[1]+1;
if 'b' then A[2]=A[2]+1;
Now in case of 2nd string for each character you decrease the values for each character found in the same array.(if you find 'a' decrease A[1] like A[1]=A[1]-1)
At last check if all the array elements are 0 or not. If 0 then definitely they are anagram else not an anagram.
Note: You may extend this for Capital letters similarly.
It is not necessary to count the crowd each letter.
Simply, you can sort your string and then check each element of two lists.
For example, you have this
"cinema" and "maneci"
It would be helpful to make your string into a list of characters.
['c','i','n','e','m','a'] and ['m','a','n','e','c','i']
Then , you can sort these list and you will check each character.
Note that you will have these cases :
example [] [] = True
example [] a = False
example a [] = False
example (h1:t1)(h2:t2) = if h1==h2 then _retroactively_ else False
In the Joy of Haskell "Finding Success and Failure", pp.11-14, the authors offer the following code which works:
import Data.List
isAnagram :: String -> String -> Bool
isAnagram word1 word2 = (sort word1) == (sort word2)
After importing your module (I imported practice.hs into Clash), you can enter two strings which, if they are anagrams, will return true:
*Practice> isAnagram "julie" "eiluj"
True
Related
I am building a puzzle word game in Python. I have the correct puzzle word, and the guessed puzzle word. I want to build a third string which shows the correct letters in the guessed puzzle in the correct puzzle word, and _ at the position of the incorrect letters.
For example, say the correct word is APPLE and the guessed word is APTLE
then i want to have a third string: AP_L_
The guessed word and correct word are guaranteed to be 3 to 5 characters long, but the guessed word is not guaranteed to be the same length as the correct word
For example, correct word is TEA and the guessed word is TEAKO, then the third string should be TEA__ because the players guessed the last two letters incorrectly.
Another example, correct word is APPLE and guessed word is POP, the third string should be:
_ _ P_ _ (without space separation)
I can successfully get the matched indexes of the correct and guessed word; however, I am having problems building the third string. I just learned that strings in Python are immutable and that i cannot assign something like str1[index] = str2[index]
I have tried many things, including using lists, but i am not getting the correct answer. The attached code is my most recent attempt, would you please help me solve this?
Thank you
find the match between puzzle_word and guess
def matcher(str_a, str_b):
#find indexes where letters overlap
matched_indexes = [i for i, (a, b) in enumerate(zip(str_a, str_b)) if a == b]
result = []
for i in str_a:
result.append('_')
for value in matched_indexes:
result[value].replace('_', str_a[value])
print(result)
matcher("apple", "allke")
the output result right now is list of five "_"
cases:
correct word is APPLE and the guessed word is APTLE third
string: AP_L_
correct word is TEA and the guessed word is TEAKO,
third string should be TEA__
correct word is APPLE and guessed
word is POP, third string should be _ _ P_ _
You can use itertools.zip_longest here to always make sure you pad out to the longest word provided and then create a new string by joining the matching characters or otherwise a _. eg:
from itertools import zip_longest
correct_and_guess = [
('APPLE', 'APTLE'),
('TEA', 'TEAKO'),
('APPLE', 'POP')
]
for correct, guess in correct_and_guess:
# If characters in same positions match - show character otherwise `_`
new_word = ''.join(c if c == g else '_' for c, g in zip_longest(correct, guess, fillvalue='_'))
print(correct, guess, new_word)
Will print the following:
APPLE APTLE AP_LE
TEA TEAKO TEA__
APPLE POP __P__
Couple of things here.
str.replace() does not replace inline; as you noted strings are immutable, so you have to assign the result of replace:
result[value] = result[value].replace('_', str_a[value])
However, there's no point doing this since you can just assign to the list element:
result[value] = str_a[value]
And finally you can assign a list of the length of str_a without the for loop, which might be more readable:
result = ['_'] * len(str_a)
I have a list of strings, and I'm trying to find the position of the first letter of the substring I am searching for in the list of strings. I'm using the find() method to do this, however when I try to print the position of the first letter Python returns the correct position but then throws a -1 after it, like it couldn't find the substring, but only after it could find it. I want to know how to return the position of the first letter of he substring without returning a -1 after the correct value.
Here is my code:
mylist = ["blasdactiverehu", "sdfsfgiuyremdn"]
word = "active"
if any(word in x for x in mylist) == True:
for x in mylist:
position = x.find(word)
print(position)
The output is:
5
-1
I expected the output to just be:
5
I think it may be related to the fact the loop is searching for the substring for every string in the list and after it's found the position it still searches for more but of course returns an error as there is only one occurrence of the substring "active", however I'm not sure how to stop searching after successfully finding one substring. Any help is appreciated, thank you.
Indeed your code will not work as you want it to, since given that any of the words contain the substring, it will do the check for each and every one of them.
A good way to avoid that is using a generator. More specifically, next()
default_val = '-1'
position = next((x.find(word) for x in mylist if word in x), default_val)
print(position)
It will simply give you the position of the substring "word" for the first string "x" that will qualify for the condition if word in x, in the list 'mylist'.
By the way, no need to check for == True when using any(), it already returns True/False, so you can simply do if any(): ...
I am trying to write a function that takes a string txt and returns an int of that string's character's ascii numbers. It also takes a second argument, n, that is an int that specified the number of digits that each character should translate to. The default value of n is 3. n is always > 3 and the string input is always non-empty.
Example outputs:
string_to_number('fff')
102102102
string_to_number('ABBA', n = 4)
65006600660065
My current strategy is to split txt into its characters by converting it into a list. Then, I convert the characters into their ord values and append this to a new list. I then try to combine the elements in this new list into a number (e.g. I would go from ['102', '102', '102'] to ['102102102']. Then I try to convert the first element of this list (aka the only element), into an integer. My current code looks like this:
def string_to_number(txt, n=3):
characters = list(txt)
ord_values = []
for character in characters:
ord_values.append(ord(character))
joined_ord_values = ''.join(ord_values)
final_number = int(joined_ord_values[0])
return final_number
The issue is that I get a Type Error. I can write code that successfully returns the integer of a single-character string, however when it comes to ones that contain more than one character, I can't because of this type error. Is there any way of fixing this. Thank you, and apologies if this is quite long.
Try this:
def string_to_number(text, n=3):
return int(''.join('{:0>{}}'.format(ord(c), n) for c in text))
print(string_to_number('fff'))
print(string_to_number('ABBA', n=4))
Output:
102102102
65006600660065
Edit: without list comprehension, as OP asked in the comment
def string_to_number(text, n=3):
l = []
for c in text:
l.append('{:0>{}}'.format(ord(c), n))
return int(''.join(l))
Useful link(s):
string formatting in python: contains pretty much everything you need to know about string formatting in python
The join method expects an array of strings, so you'll need to convert your ASCII codes into strings. This almost gets it done:
ord_values.append(str(ord(character)))
except that it doesn't respect your number-of-digits requirement.
I am trying to practice recursion, but at the moment I don't quite understand it well...
I want to write a recursive Boolean function which takes 2 strings as arguments, and returns true if the second string can be made equal to the first by replacing some letters with a certain special character.
I'll demonstrate what I mean:
Let s1 = "hello", s2 = "h%lo", where '%' is the special character.
The function will return true since '%' can replace "el", causing the two strings to be equal.
Another example:
Let s1 = "hello", s2 = "h%l".
The function will return false since an 'o' is lacking in the second string, and there is no special character that can replace the 'o' (h%l% would return true).
Now the problem isn't so much with writing the code, but with understanding how to solve the problem in general, I don't even know where to begin.
If someone could guide me in the right direction I would be very grateful, even by just using English words, I'll try to translate it to code (Java)...
Thank you.
So this is relatively easy to do in Python. The method I chose was to put the first string ("hello") into an array then iterate over the second string ("h%lo") comparing the elements to those in the array. If the element was in the array i.e. 'h', 'l', 'o' then I would pop it from the array. The resulting array is then ['e','l']. The special character can be found as it is the element which does not exist in the initial array.
One can then substitute the special character for the joined array "el" in the string and compare with the first string.
In the first case this will give "hello" == "hello" -> True
In the second case this will give "hello" == "helol" -> False
I hope this helps and makes sense.
I am new to python, and when I search for a way to get a string length without using "len()", I found this answer:
sum([1 for _ in "your string goes here"])
Can someone help me understand this line,what's the '1' doing there for example?
This is basically equivalent to this:
lst = []
for dontCareAboutTheName in "your string goes here":
lst.append(1)
print(sum(lst))
The list comprehension basically collects the number 1 for each character it finds while looping through the string. So the list will contain exactly as many elements as the length of the string. And since all those list elements are 1, when calculating the sum of all those elements, you end up with the length of the string.