Say we have a function that translates the morse symbols:
. -> -.
- -> ...-
If we apply this function twice, we get e.g:
. -> -. -> ...--.
Given an input string and a number of repetitions, want to know the length of the final string. (Problem 1 from the Flemish Programming Contest VPW, taken from these slides which provide a solution in Haskell).
For the given inputfile
4
. 4
.- 2
-- 2
--... 50
We expect the solution
44
16
20
34028664377246354505728
Since I don't know Haskell, this is my recursive solution in Python that I came up with:
def encode(msg, repetition, morse={'.': '-.', '-': '...-'}):
if isinstance(repetition, str):
repetition = eval(repetition)
while repetition > 0:
newmsg = ''.join(morse[c] for c in msg)
return encode(newmsg, repetition-1)
return len(msg)
def problem1(fn):
with open(fn) as f:
f.next()
for line in f:
print encode(*line.split())
which works for the first three inputs but dies with a memory error for the last input.
How would you rewrite this in a more efficient way?
Edit
Rewrite based on the comments given:
def encode(p, s, repetition):
while repetition > 0:
p,s = p + 3*s, p + s
return encode(p, s, repetition-1)
return p + s
def problem1(fn):
with open(fn) as f:
f.next()
for line in f:
msg, repetition = line.split()
print encode(msg.count('.'), msg.count('-'), int(repetition))
Comments on style and further improvements still welcome
Consider that you don't actually have to output the resulting string, only the length of it. Also consider that the order of '.' and '-' in the string do not affect the final length (e.g. ".- 3" and "-. 3" produce the same final length).
Thus, I would give up on storing the entire string and instead store the number of '.' and the number of '-' as integers.
In your starting string, count the number of dots and dashes. Then apply this:
repetitions = 4
dots = 1
dashes = 0
for i in range(repetitions):
dots, dashes = dots + 3 * dashes, dashes + dots
Think about it why this works.
Per #Hammar (I had the same idea, but he explained it better than I could have ;-):
from sympy import Matrix
t = Matrix([[1,3],[1,1]])
def encode(dots, dashes, reps):
res = matrix([dashes, dots]) * t**reps
return res[0,0] + res[0,1]
you put the count of dots to dashes, and count of dashes to dots in each iteration...
def encode(dots, dashes, repetitions):
while repetitions > 0:
dots, dashes = dots + 3 * dashes, dots + dashes
repetitions -= 1
return dots + dashes
def problem1(fn):
with open(fn) as f:
count = int(next(f))
for i in xrange(count):
line = next(f)
msg, repetition = line.strip().split()
print encode(msg.count('.'), msg.count('-'), int(repetition))
Related
After reading a text, I need to add 1 to a sum if I find a ( character, and subtract 1 if I find a ) character in the text. I can't figure out what I'm doing wrong.
This is what I tried at first:
file = open("day12015.txt")
sum = 0
up = "("
for item in file:
if item is up:
sum += 1
else:
sum -= 1
print(sum)
I have this long text like the following example (((())))((((( .... If I find a ), I need to subtract 1, if I find a (, I need to add 1. How can I solve it? I'm always getting 0 as output even if I change my file manually.
your for loop only gets all the string in the file so you have to loop through the string to get your desired output.
Example .txt
(((())))(((((
Full Code
file = open("Data.txt")
sum = 0
up = "("
for string in file:
for item in string:
if item is up:
sum += 1
else:
sum -= 1
print(sum)
Output
5
Hope this helps.Happy Coding :)
So you need to sum +1 for "(" character and -1 for ")".
Do it directly specifying what to occur when you encounter this character. Also you need to read the lines from a file as you're opening it. In your code, you are substracting one for every case that is not "(".
file = open("day12015.txt")
total = 0
for line in file:
for character in line:
if character == "(":
total += 1
elif character == ")":
total -= 1
print(sum)
That's simply a matter of counting each character in the text. The sum is the difference between those counts. Look:
from pathlib import Path
file = Path('day12015.txt')
text = file.read_text()
total = text.count('(') - text.count(')')
For the string you posted, for example, we have this:
>>> p = '(((())))((((('
>>> p.count('(') - p.count(')')
5
>>>
Just for comparison and out of curiosity, I timed the str.count() and a loop approach, 1,000 times, using a string composed of 1,000,000 randoms ( and ). Here is what I found:
import random
from timeit import timeit
random.seed(0)
p = ''.join(random.choice('()') for _ in range(1_000_000))
def f():
return p.count('(') - p.count(')')
def g():
a, b = 0, 0
for c in p:
if c == '(':
a = a + 1
else:
b = b + 1
return a - b
print('f: %5.2f s' % timeit(f, number=1_000))
print('g: %5.2f s' % timeit(g, number=1_000))
f: 8.19 s
g: 49.34 s
It means the loop approach is 6 times slower, even though the str.count() one is iterating over p two times to compute the result.
Input:
string = "My dear adventurer, do you understand the nature of the given discussion?"
expected output:
string = 'My dear ##########, do you ########## the nature ## the given ##########?'
How can you replace the third word in a string of words with the # length equivalent of that word while avoiding counting special characters found in the string such as apostrophes('), quotations("), full stops(.), commas(,), exclamations(!), question marks(?), colons(:) and semicolons (;).
I took the approach of converting the string to a list of elements but am finding difficulty filtering out the special characters and replacing the words with the # equivalent. Is there a better way to go about it?
I solved it with:
s = "My dear adventurer, do you understand the nature of the given discussion?"
def replace_alphabet_with_char(word: str, replacement: str) -> str:
new_word = []
alphabet = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
for c in word:
if c in alphabet:
new_word.append(replacement)
else:
new_word.append(c)
return "".join(new_word)
every_nth_word = 3
s_split = s.split(' ')
result = " ".join([replace_alphabet_with_char(s_split[i], '#') if i % every_nth_word == every_nth_word - 1 else s_split[i] for i in range(len(s_split))])
print(result)
Output:
My dear ##########, do you ########## the nature ## the given ##########?
There are more efficient ways to solve this question, but I hope this is the simplest!
My approach is:
Split the sentence into a list of the words
Using that, make a list of every third word.
Remove unwanted characters from this
Replace third words in original string with # times the length of the word.
Here's the code (explained in comments) :
# original line
line = "My dear adventurer, do you understand the nature of the given discussion?"
# printing original line
print(f'\n\nOriginal Line:\n"{line}"\n')
# printing somehting to indicate that next few prints will be for showing what is happenning after each lone
print('\n\nStages of parsing:')
# splitting by spaces, into list
wordList = line.split(' ')
# printing wordlist
print(wordList)
# making list of every third word
thirdWordList = [wordList[i-1] for i in range(1,len(wordList)+1) if i%3==0]
# pritning third-word list
print(thirdWordList)
# characters that you don't want hashed
unwantedCharacters = ['.','/','|','?','!','_','"',',','-','#','\n','\\',':',';','(',')','<','>','{','}','[',']','%','*','&','+']
# replacing these characters by empty strings in the list of third-words
for unwantedchar in unwantedCharacters:
for i in range(0,len(thirdWordList)):
thirdWordList[i] = thirdWordList[i].replace(unwantedchar,'')
# printing third word list, now without punctuation
print(thirdWordList)
# replacing with #
for word in thirdWordList:
line = line.replace(word,len(word)*'#')
# Voila! Printing the result:
print(f'\n\nFinal Output:\n"{line}"\n\n')
Hope this helps!
Following works and does not use regular expressions
special_chars = {'.','/','|','?','!','_','"',',','-','#','\n','\\'}
def format_word(w, fill):
if w[-1] in special_chars:
return fill*(len(w) - 1) + w[-1]
else:
return fill*len(w)
def obscure(string, every=3, fill='#'):
return ' '.join(
(format_word(w, fill) if (i+1) % every == 0 else w)
for (i, w) in enumerate(string.split())
)
Here are some example usage
In [15]: obscure(string)
Out[15]: 'My dear ##########, do you ########## the nature ## the given ##########?'
In [16]: obscure(string, 4)
Out[16]: 'My dear adventurer, ## you understand the ###### of the given ##########?'
In [17]: obscure(string, 3, '?')
Out[17]: 'My dear ??????????, do you ?????????? the nature ?? the given ???????????'
With help of some regex. Explanation in the comments.
import re
imp = "My dear adventurer, do you understand the nature of the given discussion?"
every_nth = 3 # in case you want to change this later
out_list = []
# split the input at spaces, enumerate the parts for looping
for idx, word in enumerate(imp.split(' ')):
# only do the special logic for multiples of n (0-indexed, thus +1)
if (idx + 1) % every_nth == 0:
# find how many special chars there are in the current segment
len_special_chars = len(re.findall(r'[.,!?:;\'"]', word))
# ^ add more special chars here if needed
# subtract the number of special chars from the length of segment
str_len = len(word) - len_special_chars
# repeat '#' for every non-special char and add the special chars
out_list.append('#'*str_len + word[-len_special_chars] if len_special_chars > 0 else '')
else:
# if the index is not a multiple of n, just add the word
out_list.append(word)
print(' '.join(out_list))
A mixed of regex and string manipulation
import re
string = "My dear adventurer, do you understand the nature of the given discussion?"
new_string = []
for i, s in enumerate(string.split()):
if (i+1) % 3 == 0:
s = re.sub(r'[^\.:,;\'"!\?]', '#', s)
new_string.append(s)
new_string = ' '.join(new_string)
print(new_string)
I have a textfile as:
-- Generated ]
FILEUNIT
METRIC /
Hello
-- timestep: Jan 01,2017 00:00:00
3*2 344.0392 343.4564 343.7741
343.9302 343.3884 343.7685 0.0000 341.0843
342.2441 342.5899 343.0728 343.4850 342.8882
342.0056 342.0564 341.9619 341.8840 342.0447 /
I have written a code to read the file and remove the words, characters and empty lines, and do some other processes on that and finally return those numbers in the last four lines. I cannot understand how to put all the numbers of the text file properly in a list. Right now the new_line generates a string of those lines with numbers
import string
def expand(chunk):
l = chunk.split("*")
chunk = [str(float(l[1]))] * int(l[0])
return chunk
with open('old_textfile.txt', 'r') as infile1:
for line in infile1:
if set(string.ascii_letters.replace("e","")) & set(line):
continue
chunks = line.split(" ")
#Get rid of newlines
chunks = list(map(lambda chunk: chunk.strip(), chunks))
if "/" in chunks:
chunks.remove("/")
new_chunks = []
for i in range(len(chunks)):
if '*' in chunks[i]:
new_chunks += expand(chunks[i])
else:
new_chunks.append(chunks[i])
new_chunks[len(new_chunks)-1] = new_chunks[len(new_chunks)-1]+"\n"
new_line = " ".join(new_chunks)
when I use the
A = new_line.split()
B = list(map(float, A))
it returns an empty list. Do you have any idea how I can put all these numbers in one single list?
currently, I am writing the new_line as a textfile and reading it again, but it increase my runtime which is not good.
f = open('new_textfile.txt').read()
A = f.split()
B = list(map(float, A))
list_1.extend(B)
There was another solution to use Regex, but it deletes 3*2. I want to process that as 2 2 2
import re
with open('old_textfile.txt', 'r') as infile1:
lines = infile1.read()
nums = re.findall(r'\d+\.\d+', lines)
print(nums)
I'm not quite sure if I entirely understand what you are trying to do, but as I understand it you want to extract all numbers which either are in a decimal form \d+\.\d+ or an integer which is multiplied by another integer using an asterisk, so \d+\*\d+. You want the results all in a list of floats where the decimals are in the list directly and for the integers the second is repeated by the first.
One way to do this would be:
lines = """
-- Generated ]
FILEUNIT
METRIC /
Hello
-- timestep: Jan 01,2017 00:00:00
3*2 344.0392 343.4564 343.7741
343.9302 343.3884 343.7685 0.0000 341.0843
342.2441 342.5899 343.0728 343.4850 342.8882
342.0056 342.0564 341.9619 341.8840 342.0447 /
"""
nums = []
for n in re.findall(r'(\d+\.\d+|\d+\*\d+)', lines):
split_by_ast = n.split("*")
if len(split_by_ast) == 1:
nums += [float(split_by_ast[0])]
else:
nums += [float(split_by_ast[1])] * int(split_by_ast[0])
print(nums)
Which returns:
[2.0, 2.0, 2.0, 344.0392, 343.4564, 343.7741, 343.9302, 343.3884, 343.7685, 0.0, 341.0843, 342.2441, 342.5899, 343.0728, 343.485, 342.8882, 342.0056, 342.0564, 341.9619, 341.884, 342.0447]
The regular expression searches for numbers matching one of the formats (decimal or int*int). Then in case of a decimal it is directly appended to the list, in case of int*int it is parsed to a smaller list repeating the second int by first int times, then the lists are concatenated.
I was wondering if anyone could help provide some insight on the following problem that I am currently struggling with.
Let's assume that you have a file that contains the following characters:
|**********|
You have another file that contains a pattern, such as:
-
/-\
/---\
/-----\
/-------\
How would you go about replacing the characters in the pattern with the characters from the first file BUT at the same time - you can only print the specific number of *'s that are in the first file.
Once you have printed say the 10 stars, in total, you have to STOP printing.
So it would be something like:
*
***
*****
*
Any hints or tips or help would be greatly appreciated.
I have been using .replace() to replace all of the characters in the pattern with the '*' but I am unable to print the specific amount only.
for ch in ['-', '/', '\\']:
if ch in form:
form = form.replace(ch, '*')
Here's my aestric file(aestricks.txt), which contains:
************
And pattern file (pattern.txt), which contains:
-
/-\
/---\
/-----\
/-------\
And here's the code. I know it can be optimized a little more, but I am posting the basic one:
file1 = open("aestricks.txt","r")
file1 = file1.read()
t_c = len(file1)
form = open("pattern.txt","r")
form = form.read()
form1 = form
count = 0
for ch in form1:
if ch in ['-','/', '\\']:
form = form.replace(ch, '*', 1)
count += 1
if count == t_c:
break
for ch in form1:
if ch in ['-','/', '\\']:
form = form.replace(ch, '')
print(form)
OUTPUT:
*
***
*****
***
You can use regular expressions and sub() function from re module.
sub() takes an optional count argument that indicates the maximal number of pattern occurrences to be replaced.
import re
with open('asterisks.txt') as asterisks_file, open('ascii_art.txt') as ascii_art_file:
pattern = re.compile(r'[' # match one from within square brackets:
r'\\' # either backslash
r'/' # or slash
r'-' # or hyphen
r']')
# let n be the number of asterisks from the first file
n = asterisks_file.read().count('*')
# replace first n matches of our pattern (one of /\- characters)
replaced_b = pattern.sub('*', ascii_art_file.read(), n)
# replace rest of the /\- characters with spaces (based on your example)
result = pattern.sub(' ', replaced_b)
print(result)
OUTPUT:
*
***
*****
*
Instead of replacing every character at once you can replace items one at a time and use some count on number of replacements.
But str object doesn't support item assignment at specific index, so you have to convert the str object into list first. Then do your operations and convert back to str again.
you can write something like this.
characters = ['-', '/', '\\']
count = 0
a = list(form) # convert your string to list
for i in range(len(a)):
if a[i] in characters and count < 10: # iterate through each character
a[i] = '*' # replace with '*'
count += 1 # increment count
result = "".join(a) # convert list back into str
print(result)
import re
file1 = open("file1.txt", "r")
s=file1.read()
starcount=s.count('*')
file2 = open("file2.txt", "r")
line = re.sub(r'[-|\\|/]', r'*', file2.read(), starcount)
line = re.sub(r'[-|\\|/]', r'', line)
print(line)
Syntax of sub
>>> import re
>>> help(re.sub)
Help on function sub in module re:
sub(pattern, repl, string, count=0, flags=0)
Return the string obtained by replacing the leftmost
non-overlapping occurrences of the pattern in string by the
replacement repl. repl can be either a string or a callable;
if a string, backslash escapes in it are processed. If it is
a callable, it's passed the match object and must return
a replacement string to be used.
Output
*
***
*****
*
Demo
https://repl.it/repls/ObeseNoteworthyDevelopment
You just need to keep track of the number of * in the input line and then continue to replace the dashes until the counter runs out. Once the counter runs out then replace the remaining dashes with empty strings.
def replace(p, s):
counter = len(s) - 2
chars = ['\\', '/', '-']
i = 0
for c in p:
if c in chars:
p = p.replace(c, '*', 1)
i += 1
if i == counter:
break
p = p.replace('\\', '')
p = p.replace('/', '')
p = p.replace('-', '')
return p
if __name__ == '__main__':
stars = '|**********|'
pyramid = r'''
-
/-\
/---\
/-----\
/-------\ '''
print(pyramid)
print(replace(pyramid, stars))
OUTPUT
*
***
*****
*
import re
inp = open('stars.txt', 'r').read()
count = len(inp.strip('|')) #stripping off the extra characters from either end
pattern = open('pattern.txt', 'r').read() # read the entire pattern
out = re.sub(r'-|/|\\', r'*', pattern, count=count) # for any of the characters in '-' or '|' or '\', replace them with a '*' only **count** number of times.
out = re.sub(r'-|/|\\', r'', out) # to remove the left out characters
print (out)
Added one more re.sub line to remove the left out characters if any.
so -----2-----3----5----2----3----- would become -----4-----5----7----4----5-----
if the constant was 2 and etc. for every individual line in the text file.
This would involve splitting recognising numbers in between strings and adding a constant to them e.g ---15--- becomes ---17--- not ---35---.
(basically getting a guitar tab and adding a constant to every fret number)
Thanks. Realised this started out vague and confusing so sorry about that.
lets say the file is:
-2--3--5---7--1/n-6---3--5-1---5
and im adding 2, it should become:
-4--5--7---9--3/n-8---5--7-3---7
Change the filename to something relevant and this code will work. Anything below new_string needs to be change for what you need, eg writing to a file.
def addXToAllNum(int: delta, str: line):
values = [x for x in s.split('-') if x.isdigit()]
values = [str(int(x) + delta) for x in values]
return '--'.join(values)
new_string = '' # change this section to save to new file
for line in open('tabfile.txt', 'r'):
new_string += addXToAllNum(delta, line) + '\n'
## general principle
s = '-4--5--7---9--3 -8---5--7-3---7'
addXToAllNum(2, s) #6--7--9--11--10--7--9--5--9
This takes all numbers and increments by the shift regardless of the type of separating characters.
import re
shift = 2
numStr = "---1----9---15---"
print("Input: " + numStr)
resStr = ""
m = re.search("[0-9]+", numStr)
while (m):
resStr += numStr[:m.start(0)]
resStr += str(int(m.group(0)) + shift)
numStr = numStr[m.end(0):]
m = re.search("[0-9]+", numStr)
resStr += numStr
print("Result:" + resStr)
Hi You Can use that to betwine every line in text file add -
rt = ''
f = open('a.txt','r')
app = f.readlines()
for i in app:
rt+=str(i)+'-'
print " ".join(rt.split())
import re
c = 2 # in this example, the increment constant value is 2
with open ('<your file path here>', 'r+') as file:
new_content = re.sub (r'\d+', lambda m : str (int (m.group (0)) + c), file.read ())
file.seek (0)
file.write (new_content)