How to compress string in python I am not getting proper output can you please help me

Question

string s is given as input
ex-aaabb
output-3a2b
ex-"bbcd"
output-2bcd
here we are count frequency of each character and we have to display their count with that character
https://code.sololearn.com/cBVuy2M68ul6/?ref=app

Answer 1

Gordon, storing individual letters in the dictionary
with their frequency will allow you to work only
with sequences like 'aaabb' not with 'aaabbaabbb'

st = input() or 'aaabbaabbb'
d = dict (zip (list(st), map (st.count, st)))
print(''.join ([str(d[i]) + i for i in d]))

output is '5a5b' , but should be '3a2b2a3b'

i made it like this:
https://code.sololearn.com/c2206HU7VFDA/?ref=app

Answer 2

Looping through the string is correct

instead of using only one count variable and comparing with the first char only,

Use a dictionary to store count

count = {} # before the loop

If the current char has not existed in the dictionary as a key, initialize by setting its value as 1.

if not ch in count:
count[ch] = 1

otherwise increment by 1.

else:
count[ch] = count[ch] + 1

at last, loop through the dictionary to display the result.

Answer 3

If we are talking about RLE (run length encoded) we can use python itertools takewhile(). It does group consecutive characters, that can be encoded in an easy way.

Answer 4

rodwynnejones, your code sample does collect for example all "a", so the output is not correct in terms of RLE:

7a6b4c

Answer 5

Here is a code that works with itertools groupby()
https://code.sololearn.com/cH6ss6iK6EP8/?ref=app

Answer 6

May be you should have a look first of all to what the code is producing:

Input string:
abbc deffg hiiki

result from program:
1a2b1a2b1c1 1d1e2f1a2b1c1 1d1e2f1g1 1h2i

result expected:
1a2b1c 1d1e2f1g 1h2i1k1i

if spaces should be also handled, encoding should be like this:
1a2b1c1 1d1e2f1g1 1h2i1k1i

Answer 7

lothar
ahh I see...I was not aware of the RLE thing (i just now googled it)...and I hadn't understood the requirement correctly.

Answer 8

Shelly Kapoor
Is your input one single word string i.e. no spaces?
Have a look at regular expressions. (re.findall)...I've had a go using re (after I finally understood what your trying to do). Here's the pattern I used:

mystring = "aaabbaabbbbc"
pattern = '+|'.join(set(mystring)) + '+'

https://code.sololearn.com/cIKvkA7HZdHq/#py

Answer 9

Shelly Kapoor any feedback about answer solutions you got?

Answer 10

Vitaly Sokol Why do you think that it won't work for aaabbaabbbb?

https://code.sololearn.com/cjwW0ypPO75g/?ref=app

JSON is applicable to any programming language ~

Answer 11

Gordon, How can we restore the original sequence
from its compressed form '5a5b'?
We need compression in the form of '3a2b2a3b'
to restore the original string, as I understand it.

Answer 12

Vitaly Sokol 🤔 I don't see the need for decompression in the original question.

But I can see your point now.

Answer 13

mystring = "aaabbaabbccaabbcc"
for x in sorted(set(mystring)):
print(mystring.count(x), x, sep='', end='')

or you can use the "Counter" from the "collections" module.