How to make a continuous alphabetic list python (from a-z then from aa, ab, ac etc)

I would like to make a alphabetical list for an application similar to an excel worksheet.

A user would input number of cells and I would like to generate list.
For example a user needs 54 cells. Then I would generate

‘a’,’b’,’c’,…,’z’,’aa’,’ab’,’ac’,…,’az’, ‘ba’,’bb’

I can generate the list from [ref]

 from string import ascii_lowercase
 L = list(ascii_lowercase)

How do i stitch it together?
A similar question for PHP has been asked here. Does some one have the python equivalent?

Answers:

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Method 1

Use itertools.product.

from string import ascii_lowercase
import itertools

def iter_all_strings():
    for size in itertools.count(1):
        for s in itertools.product(ascii_lowercase, repeat=size):
            yield "".join(s)

for s in iter_all_strings():
    print(s)
    if s == 'bb':
        break

Result:

a
b
c
d
e
...
y
z
aa
ab
ac
...
ay
az
ba
bb

This has the added benefit of going well beyond two-letter combinations. If you need a million strings, it will happily give you three and four and five letter strings.

Bonus style tip: if you don’t like having an explicit break inside the bottom loop, you can use islice to make the loop terminate on its own:

for s in itertools.islice(iter_all_strings(), 54):
    print s

Method 2

You can use a list comprehension.

from string import ascii_lowercase
L = list(ascii_lowercase) + [letter1+letter2 for letter1 in ascii_lowercase for letter2 in ascii_lowercase]

Method 3

Following @Kevin ‘s answer :

from string import ascii_lowercase
import itertools

# define the generator itself
def iter_all_strings():
    size = 1
    while True:
        for s in itertools.product(ascii_lowercase, repeat=size):
            yield "".join(s)
        size +=1

The code below enables one to generate strings, that can be used to generate unique labels for example.

# define the generator handler
gen = iter_all_strings()
def label_gen():
    for s in gen:
        return s

# call it whenever needed
print label_gen()
print label_gen()
print label_gen()

Method 4

I’ve ended up doing my own.
I think it can create any number of letters.

def AA(n, s):
    r = n % 26
    r = r if r > 0 else 26
    n = (n - r) / 26
    s = chr(64 + r) + s

    if n > 26: 
        s = AA(n, s)
    elif n > 0:
        s = chr(64 + n) + s

    return s

n = quantity | r = remaining (26 letters A-Z) | s = string

To print the list :

def uprint(nc):
    for x in range(1, nc + 1):
        print AA(x,'').lower()

Used VBA before convert to python :

Function AA(n, s)

    r = n Mod 26
    r = IIf(r > 0, r, 26)
    n = (n - r) / 26
    s = Chr(64 + r) & s

    If n > 26 Then
        s = AA(n, s)
    ElseIf n > 0 Then
        s = Chr(64 + n) & s
    End If

    AA = s

End Function

Method 5

Using neo’s insight on a while loop.
For a given iterable with chars in ascending order. ‘abcd…’.
n is the Nth position of the representation starting with 1 as the first position.

def char_label(n, chars):
    indexes = []
    while n:
        residual = n % len(chars)
        if residual == 0:
            residual = len(chars)
        indexes.append(residual)
        n = (n - residual)
        n = n // len(chars)
    indexes.reverse()
    label = ''
    for i in indexes:
        label += chars[i-1]
    return label

Later you can print a list of the range n of the ‘labels’ you need using a for loop:

my_chrs = 'abc'
n = 15
for i in range(1, n+1):
    print(char_label(i, my_chrs))

or build a list comprehension etc…

Method 6

Print the set of xl cell range of lowercase and uppercase charterers

Upper_case:

from string import ascii_uppercase
import itertools
def iter_range_strings(start_colu):
    for size in itertools.count(1):
        for string  in itertools.product(ascii_uppercase, repeat=size):
            yield "".join(string)

input_colume_range = ['A', 'B']
input_row_range= [1,2]
for row in iter_range_strings(input_colume_range[0]):
    for colum in range(int(input_row_range[0]), int(input_row_range[1]+1)):
        print(str(row)+ str(colum))
    if row ==  input_colume_range[1]:
        break

Result:

A1
A2
B1
B2

Method 7

In two lines (plus an import):

from string import ascii_uppercase as ABC

count = 100
ABC+=' '
[(ABC[x[0]] + ABC[x[1]]).strip() for i in range(count) if (x:= divmod(i-26, 26))]

Wrap it in a function/lambda if you need to reuse.

Method 8

code:

alphabet = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]
for i in range(len(alphabet)):
    for a in range(len(alphabet)):
        print(alphabet[i] + alphabet[a])

result:

aa
ab
ac
ad
ae
af
ag
ah
ai
aj
ak
al
am
...

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0