How to make a continuous alphabetic list python (from a-z then from aa, ab, ac etc)
Question:
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:
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]
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
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()
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
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
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.
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…
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
...
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?
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]
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
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()
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
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
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.
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…
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
...