My code
l=['99','08','096']
for i in l:
if i.startswith('0'):
i.replace('0','')
print(l)
Output
l=['99','08','096']
I just want to remove the leading '0's from all the strings:
l=['99','8','96']
You can use str.lstrip() for this in a list comprehension - to remove all leading '0's from each string.
>>> l = ['99', '08', '096']
>>> [x.lstrip('0') for x in l]
['99', '8', '96']
This has the added benefit of not removing instances of '0' from within the string, only from the front.
>>> l=['99', '08', '096', '0102']
>>> [x.lstrip('0') for x in l]
['99', '8', '96', '102']
If I understood you correctly, you want to remove the string from the array if it starts with 0, but from the code you showed, you are just replacing the 0 in the string with nothing. i.replace('0','')
one way to filter out is:
new_list = [el for el in l if not el.startswith('0')]
you can use list comprehension to correct your strings by using str.lstrip:
[e.lstrip('0') for e in l]
or you can use a for loop:
for i in range(len(l)):
if l[i].startswith('0'):
l[i] = l[i][1:]
I have a list = ['01', '25', '47', '57']
how can I iteratively or recursively merge the element until the final list is ['01','2574']?
You can use a while loop to keep looking for the next pair of characters in the list that matches the last character in the last string in the output list, concatenate the other character in the pair to the string if a match is found, or append the first string to the output list if there is no match, and remove the matching string or the first string from the input list until the list becomes empty:
lst = ['01', '25', '47', '57']
output = []
while lst:
for i, pair in enumerate(lst):
if output and output[-1][-1] in pair:
output[-1] += pair[output[-1][-1] == pair[0]]
del lst[i]
break
else:
first, *lst = lst
output.append(first)
output becomes:
['01', '2574']
I have an input, which is a tuple of strings, encoded in a1z26 cipher: numbers from 1 to 26 represent alphabet letters, hyphens represent same word letters and spaces represent an space between words.
For example:
8-9 20-8-5-18-5 should translate to 'hi there'
Let's say that the last example is a tuple in a var called string
string = ('8-9','20-8-5-18-5')
The first thing I find logical is convert the tuple into a list using
string = list(string)
so now
string = ['8-9','20-8-5-18-5']
The problem now is that when I iterate over the list to compare it with a dictionary which has the translated values, double digit numbers are treated as one, so instead of, for example, translating '20' it translate '2' and then '0', resulting in the string saying 'hi bheahe' (2 =b, 1 = a and 8 = h)
so I need a way to convert the list above to the following
list
['8','-','9',' ','20','-','8','-','5','-','18','-','5',]
I've already tried various codes using
list(),
join() and
split()
But it ends up giving me the same problem.
To sum up, I need to make any given list (converted from the input tuple) into a list of characters that takes into account double digit numbers, spaces and hyphens altogether
This is what I've got so far. (The last I wrote) The input is further up in the code (string)
a1z26 = {'1':'A', '2':'B', '3':'C', '4':'D', '5':'E', '6':'F', '7':'G', '8':'H', '9':'I', '10':'J', '11':'K', '12':'L', '13':'M', '14':'N', '15':'O', '16':'P', '17':'Q', '18':'R', '19':'S', '20':'T', '21':'U', '22':'V', '23':'W', '24':'X', '25':'Y', '26':'Z', '-':'', ' ' : ' ', ', ' : ' '}
translation = ""
code = list(string)
numbersarray1 = code
numbersarray2 = ', '.join(numbersarray1)
for char in numbersarray2:
if char in a1z26:
translation += a1z26[char]
There's no need to convert the tuple to a list. Tuples are iterable too.
I don't think the list you name is what you actually want. You probably want a 2d iterable (not necessarily a list, as you'll see below we can do this in one pass without generating an intermediary list), where each item corresponds to a word and is a list of the character numbers:
[[8, 9], [20, 8, 5, 18, 5]]
From this, you can convert each number to a letter, join the letters together to form the words, then join the words with spaces.
To do this, you need to pass a parameter to split, to tell it how to split your input string. You can achieve all of this with a one liner:
plaintext = ' '.join(''.join(num_to_letter[int(num)] for num in word.split('-'))
for word in ciphertext.split(' '))
This does exactly the splitting procedure as described above, and then for each number looks into the dict num_to_letter to do the conversion.
Note that you don't even need this dict. You can use the fact that A-Z in unicode is contiguous so to convert 1-26 to A-Z you can do chr(ord('A') + num - 1).
You don't really need hypens, am I right?
I suggest you the following approach:
a = '- -'.join(string).split('-')
Now a is ['8', '9', ' ', '20', '8', '5', '18', '5']
You can then convert each number to the proper character using your dictionary
b = ''.join([a1z26[i] for i in a])
Now b is equal to HI THERE
I think, it's better to apply regular expressions there.
Example:
import re
...
src = ('8-9', '20-8-5-18-5')
res = [match for tmp in src for match in re.findall(r"([0-9]+|[^0-9]+)", tmp + " ")][:-1]
print(res)
Result:
['8', '-', '9', ' ', '20', '-', '8', '-', '5', '-', '18', '-', '5']
using regex here is solution
import re
string = '8-9 20-8-5-18-5'
exp=re.compile(r'[0-9]+|[^0-9]+')
data= exp.findall(string)
print(data)
output
['8', '-', '9', ' ', '20', '-', '8', '-', '5', '-', '18', '-', '5']
if you want to get hi there from the input string , here is a method (i am assuming all character are in uppercase):
import re
string = '8-9 20-8-5-18-5'
exp=re.compile(r'[0-9]+|[^0-9]+')
data= exp.findall(string)
new_str =''
for i in range(len(data)):
if data[i].isdigit():
new_str+=chr(int(data[i])+64)
else:
new_str+=data[i]
result = new_str.replace('-','')
output:
HI THERE
You could also try this itertools solution:
from itertools import chain
from itertools import zip_longest
def separate_list(lst, delim, sep=" "):
result = []
for x in lst:
chars = x.split(delim) # 1
pairs = zip_longest(chars, [delim] * (len(chars) - 1), fillvalue=sep) # 2, 3
result.extend(list(chain.from_iterable(pairs))) # 4
return result[:-1] # 5
print(separate_list(["8-9", "20-8-5-18-5"], delim="-"))
Output:
['8', '-', '9', ' ', '20', '-', '8', '-', '5', '-', '18', '-', '5']
Explanation of above code:
Split each string by delimiter '-'.
Create interspersing delimiters.
Create pairs of characters and separators with itertools.zip_longest.
Extend flattened pairs to result list with itertools.chain.from_iterable.
Remove trailing ' ' from result list added.
You could also create your own intersperse generator function and apply it twice:
from itertools import chain
def intersperse(iterable, delim):
it = iter(iterable)
yield next(it)
for x in it:
yield delim
yield x
def separate_list(lst, delim, sep=" "):
return list(
chain.from_iterable(
intersperse(
(intersperse(x.split(delim), delim=delim) for x in lst), delim=[sep]
)
)
)
print(separate_list(["8-9", "20-8-5-18-5"], delim="-"))
# ['8', '-', '9', ' ', '20', '-', '8', '-', '5', '-', '18', '-', '5']
I have a list:
my_list = ['0300', '0023', '0005', '000030']
I want to remove the preceding zeroes in each string element from the list. So I want strip the 0s from the left side of the string.
Output would be like this:
my_list = ['300', '23', '5', '30']
I've tried this:
for x in my_list:
x = re.sub(r'^0+', "", x)
print my_list
But it doesn't seem to work. Please help!
You can use str.lstrip like this
print [item.lstrip('0') for item in l]
# ['300', '23', '5', '30']
Try:
list = [str(int(el)) for el in list]
Edit: pick the other answer, I'd prefer that one too :-)
In the nested list:
x = [['0', '-', '3', '2'], ['-', '0', '-', '1', '3']]
how do I remove the hyphens?
x = x.replace("-", "")
gives me AttributeError: 'list' object has no attribute 'replace', and
print x.remove("-")
gives me ValueError: list.remove(x): x not in list.
x is a list of lists. replace() will substitute a pattern string for another within a string. What you want is to remove an item from a list. remove() will remove the first occurrence of an item. A simple approach:
for l in x:
while ("-" in l):
l.remove("-")
For more advanced solutions, see the following: Remove all occurrences of a value from a Python list