Develop Reference

Regex: Split characters with "/"

I have these strings, for example:
['2300LO/LCE','2302KO/KCE']
I want to have output like this:
['2300LO','2300LCE','2302KO','2302KCE']
How can I do it with Regex in Python?
Thanks!

You can make a simple generator that yields the pairs for each string. Then you can flatten them into a single list with itertools.chain()
from itertools import product, chain
def getCombos(s):
nums, code = re.match(r'(\d+)(.*)', s).groups()
for pair in product([nums], code.split("/")):
yield ''.join(pair)
a = ['2300LO/LCE','2302KO/KCE']
list(chain.from_iterable(map(getCombos, a)))
# ['2300LO', '2300LCE', '2302KO', '2302KCE']
This has the added side benefit or working with strings like '2300LO/LCE/XX/CC' which will give you ['2300LO', '2300LCE', '2300XX', '2300CC',...]

You can try something like this:
list1 = ['2300LO/LCE','2302KO/KCE']
list2 = []
for x in list1:
a = x.split('/')
tmp = re.findall(r'\d+', a[0]) # extracting digits
list2.append(a[0])
list2.append(tmp[0] + a[1])
print(list2)

This can be implemented with simple string splits.
Since you asked the output with regex, here is your answer.
list1 = ['2300LO/LCE','2302KO/KCE']
import re
r = re.compile("([0-9]{1,4})([a-zA-Z].*)/([a-zA-Z].*)")
out = []
for s in list1:
items = r.findall(s)[0]
out.append(items[0]+items[1])
out.append(items[2])
print(out)
The explanation for the regex - (4 digit number), followed by (any characters), followed by a / and (rest of the characters).
they are grouped with () , so that when you use find all, it becomes individual elements.

pattern match get list and dict from string

I have string below,and I want to get list,dict,var from this string.
How can I to split this string to specific format?
s = 'list_c=[1,2],a=3,b=1.3,c=abch,list_a=[1,2],dict_a={a:2,b:3}'
import re
m1 = re.findall (r'(?=.*,)(.*?=\[.+?\],?)',s)
for i in m1 :
print('m1:',i)
I only get result 1 correctly.
Does anyone know how to do?
m1: list_c=[1,2],
m1: a=3,b=1.3,c=abch,list_a=[1,2],

Use '=' to split instead, then you can work around with variable name and it's value.
You still need to handle the type casting for values (regex, split, try with casting may help).
Also, same as others' comment, using dict may be easier to handle
s = 'list_c=[1,2],a=3,b=1.3,c=abch,list_a=[1,2],dict_a={a:2,b:3}'
al = s.split('=')
var_l = [al[0]]
value_l = []
for a in al[1:-1]:
var_l.append(a.split(',')[-1])
value_l.append(','.join(a.split(',')[:-1]))
value_l.append(al[-1])
output = dict(zip(var_l, value_l))
print(output)

You may have better luck if you more or less explicitly describe the right-hand side expressions: numbers, lists, dictionaries, and identifiers:
re.findall(r"([^=]+)=" # LHS and assignment operator
+r"([+-]?\d+(?:\.\d+)?|" # Numbers
+r"[+-]?\d+\.|" # More numbers
+r"\[[^]]+\]|" # Lists
+r"{[^}]+}|" # Dictionaries
+r"[a-zA-Z_][a-zA-Z_\d]*)", # Idents
s)
# [('list_c', '[1,2]'), ('a', '3'), ('b', '1.3'), ('c', 'abch'),
# ('list_a', '[1,2]'), ('dict_a', '{a:2,b:3}')]

The answer is like below
import re
from pprint import pprint
s = 'list_c=[1,2],a=3,b=1.3,c=abch,list_a=[1],Save,Record,dict_a={a:2,b:3}'
m1 = re.findall(r"([^=]+)=" # LHS and assignment operator
+r"([+-]?\d+(?:\.\d+)?|" # Numbers
+r"[+-]?\d+\.|" # More numbers
+r"\[[^]]+\]|" # Lists
+r"{[^}]+}|" # Dictionaries
+r"[a-zA-Z_][a-zA-Z_\d]*)", # Idents
s)
temp_d = {}
for i,j in m1:
temp = i.strip(',').split(',')
if len(temp)>1:
for k in temp[:-1]:
temp_d[k]=''
temp_d[temp[-1]] = j
else:
temp_d[temp[0]] = j
pprint(temp_d)
Output is like
{'Record': '',
'Save': '',
'a': '3',
'b': '1.3',
'c': 'abch',
'dict_a': '{a:2,b:3}',
'list_a': '[1]',
'list_c': '[1,2]'}

Instead of picking out the types, you can start by capturing the identifiers. Here's a regex that captures all the identifiers in the string (for lowercase only, but see note):
regex = re.compile(r'([a-z]|_)+=')
#note if you want all valid variable names: r'([a-z]|[A-Z]|[0-9]|_)+'
cases = [x.group() for x in re.finditer(regex, s)]
This gives a list of all the identifiers in the string:
['list_c=', 'a=', 'b=', 'c=', 'list_a=', 'dict_a=']
We can now define a function to sequentially chop up s using the
above list to partition the string sequentially:
def chop(mystr, mylist):
temp = mystr.partition(mylist[0])[2]
cut = temp.find(mylist[1]) #strip leading bits
return mystr.partition(mylist[0])[2][cut:], mylist[1:]
mystr = s[:]
temp = [mystr]
mylist = cases[:]
while len() > 1:
mystr, mylist = chop(mystr, mylist)
temp.append(mystr)
This (convoluted) slicing operation gives this list of strings:
['list_c=[1,2],a=3,b=1.3,c=abch,list_a=[1,2],dict_a={a:2,b:3}',
'a=3,b=1.3,c=abch,list_a=[1,2],dict_a={a:2,b:3}',
'b=1.3,c=abch,list_a=[1,2],dict_a={a:2,b:3}',
'c=abch,list_a=[1,2],dict_a={a:2,b:3}',
'list_a=[1,2],dict_a={a:2,b:3}',
'dict_a={a:2,b:3}']
Now cut off the ends using each successive entry:
result = []
for x in range(len(temp) - 1):
cut = temp[x].find(temp[x+1]) - 1 #-1 to remove commas
result.append(temp[x][:cut])
result.append(temp.pop()) #get the last item
Now we have the full list:
['list_c=[1,2]', 'a=3', 'b=1.3', 'c=abch', 'list_a=[1,2]', 'dict_a={a:2,b:3}']
Each element is easily parsable into key:value pairs (and is also executable via exec).

Cut character string every two commas

I would like to separate my string every both commas but I can not, can you help me.
This is what I want: ['nb1,nb2','nb3,nb4','nb5,nb6']
Here is what I did :
a= 'nb1,nb2,nb3,nb4,nb5,nb6'
compteur=0
for i in a:
if i==',' :
compteur+=1
if compteur%2==0:
print compteur
test = a.split(',', compteur%2==0 )
print a
print test
The result:
2
4
nb1,nb2,nb3,nb4,nb5,nb6
['nb1', 'nb2,nb3,nb4,nb5,nb6']
Thanks you by advances for you answers

You can use regex
In [12]: re.findall(r'([\w]+,[\w]+)', 'nb1,nb2,nb3,nb4,nb5,nb6')
Out[12]: ['nb1,nb2', 'nb3,nb4', 'nb5,nb6']

A quick fix could be to simply first separate the elements by commas and then join the elements by two together again. Like:
sub_result = a.split(',')
result = [','.join(sub_result[i:i+2]) for i in range(0,len(sub_result),2)]
This gives:
>>> result
['nb1,nb2', 'nb3,nb4', 'nb5,nb6']
This will also work if the number of elements is odd. For example:
>>> a = 'nb1,nb2,nb3,nb4,nb5,nb6,nb7'
>>> sub_result = a.split(',')
>>> result = [','.join(sub_result[i:i+2]) for i in range(0,len(sub_result),2)]
>>> result
['nb1,nb2', 'nb3,nb4', 'nb5,nb6', 'nb7']

You use a zip operation of the list with itself to create pairs:
a = 'nb1,nb2,nb3,nb4,nb5,nb6'
parts = a.split(',')
# parts = ['nb1', 'nb2', 'nb3', 'nb4', 'nb5', 'nb6']
pairs = list(zip(parts, parts[1:]))
# pairs = [('nb1', 'nb2'), ('nb2', 'nb3'), ('nb3', 'nb4'), ('nb4', 'nb5'), ('nb5', 'nb6')]
Now you can simply join every other pair again for your output:
list(map(','.join, pairs[::2]))
# ['nb1,nb2', 'nb3,nb4', 'nb5,nb6']

Split the string by comma first, then apply the common idiom to partition an interable into sub-sequences of length n (where n is 2 in your case) with zip.
>>> s = 'nb1,nb2,nb3,nb4,nb5,nb6'
>>> [','.join(x) for x in zip(*[iter(s.split(','))]*2)]
['nb1,nb2', 'nb3,nb4', 'nb5,nb6']

Spliting string into two by comma using python

I have following data in a list and it is a hex number,
['aaaaa955554e']
I would like to split this into ['aaaaa9,55554e'] with a comma.
I know how to split this when there are some delimiters between but how should i do for this case?
Thanks

This will do what I think you are looking for:
yourlist = ['aaaaa955554e']
new_list = [','.join([x[i:i+6] for i in range(0, len(x), 6)]) for x in yourlist]
It will put a comma at every sixth character in each item in your list. (I am assuming you will have more than just one item in the list, and that the items are of unknown length. Not that it matters.)

i assume you wanna split into every 6th character
using regex
import re
lst = ['aaaaa955554e']
newlst = re.findall('\w{6}', lst[0])
# ['aaaaa9', '55554e']
Using list comprehension, this works for multiple items in lst
lst = ['aaaaa955554e']
newlst = [item[i:i+6] for i in range(0,len(a[0]),6) for item in lst]
# ['aaaaa9', '55554e']

This could be done using a regular expression substitution as follows:
import re
print re.sub(r'([a-zA-Z]+\d)(.*?)', r'\1,\2', 'aaaaa955554e', count=1)
Giving you:
aaaaa9,55554e
This splits after seeing the first digit.

Use of slice command with split command?

fh=open('asd.txt')
data=fh.read()
fh.close()
name=data.split('\n')[0][1:]
seq=''.join(data.split('\n')[1:])
print name
print seq
In this code, the 3rd line means "take only first line with first character removed" while the 4th line means "leave the first line and join the next remaining lines".
I cannot get the logic of these two lines.
Can anyone explain me how these two slice operators ([0][1:]) are used together?
Thanx
Edited: renamed file variable (which is a keyword, too) to data.

Think of it like this: file.split('\n') gives you a list of strings. So the first indexing operation, [0], gives you the first string in the list. Now, that string itself is a "list" of characters, so you can then do [1:] to get every character after the first. It's just like starting with a two-dimensional list (a list of lists) and indexing it twice.

When confused by a complex expression, do it it steps.
>>> data.split('\n')[0][1:]
>>> data
>>> data.split('\n')
>>> data.split('\n')[0]
>>> data.split('\n')[0][1:]
That should help.

lets do it by steps, (I think I know what name and seq is):
>>> file = ">Protein kinase\nADVTDADTSCVIN\nASHRGDTYERPLK" <- that's what you get reading your (fasta) file
>>> lines = file.split('\n') <- make a list of lines
>>> line_0 = lines[0] <- take first line (line numbers start at 0)
>>> name = line_0[1:] <- give me line items [x:y] (from x to y)
>>> name
'Protein kinase'
>>>
>>> file = ">Protein kinase\nADVTDADTSCVIN\nASHRGDTYERPLK"
>>> lines = file.split('\n')
>>> seqs = lines[1:] <- gime lines [x:y] (from x to y)
>>> seq = ''.join(seqs)
>>> seq
'ADVTDADTSCVINASHRGDTYERPLK'
>>>
in slice [x:y], x is included, y is not included. When you want to arrive to the end of the list just do not indicate y -> [x:] (from item of index x to the end)

Each set of [] just operates on the list that split returns, and the resulting
list or string then used without assigning it to another variable first.
Break down the third line like this:
lines = file.split('\n')
first_line = lines[0]
name = first_line[1:]
Break down the fourth line like this:
lines = file.split('\n')
all_but_first_line = lines[1:]
seq = ''.join(all_but_first_line)

take this as an example
myl = [["hello","world","of","python"],["python","is","good"]]
so here myl is a list of list. So, myl[0] means first element of list which is equal to ['hello', 'world', 'of', 'python'] but when you use myl[0][1:] it means selecting first element from list which is represented by myl[0] and than from the resulting list(myl[0]) select every element except first one(myl[0][1:]). So output = ['world', 'of', 'python']