Could someone please help me strip characters from a string to leave me with just the characters held within '[....]'?
For example:
a = newyork_74[mylocation]
b = # strip the frist characters until you reach the first bracket [
c = [mylocation]
Something like this:
>>> import re
>>> strs = "newyork_74[mylocation]"
>>> re.sub(r'(.*)?(\[)','\g<2>',strs)
'[mylocation]'
Assuming no nested structures, one way would be using itertools.dropwhile,
>>> from itertools import dropwhile
>>> b = ''.join(dropwhile(lambda c: c != '[', a))
>>> b
'[mylocation]'
Another would be to use regexs,
>>> import re
>>> pat = re.compile(r'\[.*\]')
>>> b = pat.search(a).group(0)
>>> b
'[mylocation]'
Related
I have a string in which I want to replace some variables, but in different steps, something like:
my_string = 'text_with_{var_1}_to_variables_{var_2}'
my_string.format(var_1='10')
### make process 1
my_string.format(var_2='22')
But when I try to replace the first variable I get an Error:
KeyError: 'var_2'
How can I accomplish this?
Edit:
I want to create a new list:
name = 'Luis'
ids = ['12344','553454','dadada']
def create_list(name,ids):
my_string = 'text_with_{var_1}_to_variables_{var_2}'.replace('{var_1}',name)
return [my_string.replace('{var_2}',_id) for _id in ids ]
this is the desired output:
['text_with_Luis_to_variables_12344',
'text_with_Luis_to_variables_553454',
'text_with_Luis_to_variables_dadada']
But using .format instead of .replace.
In simple words, you can not replace few arguments with format {var_1}, var_2 in string(not all) using format. Even though I am not sure why you want to only replace partial string, but there are few approaches that you may follow as a workaround:
Approach 1: Replacing the variable you want to replace at second step by {{}} instead of {}. For example: Replace {var_2} by {{var_2}}
>>> my_string = 'text_with_{var_1}_to_variables_{{var_2}}'
>>> my_string = my_string.format(var_1='VAR_1')
>>> my_string
'text_with_VAR_1_to_variables_{var_2}'
>>> my_string = my_string.format(var_2='VAR_2')
>>> my_string
'text_with_VAR_1_to_variables_VAR_2'
Approach 2: Replace once using format and another using %.
>>> my_string = 'text_with_{var_1}_to_variables_%(var_2)s'
# Replace first variable
>>> my_string = my_string.format(var_1='VAR_1')
>>> my_string
'text_with_VAR_1_to_variables_%(var_2)s'
# Replace second variable
>>> my_string = my_string % {'var_2': 'VAR_2'}
>>> my_string
'text_with_VAR_1_to_variables_VAR_2'
Approach 3: Adding the args to a dict and unpack it once required.
>>> my_string = 'text_with_{var_1}_to_variables_{var_2}'
>>> my_args = {}
# Assign value of `var_1`
>>> my_args['var_1'] = 'VAR_1'
# Assign value of `var_2`
>>> my_args['var_2'] = 'VAR_2'
>>> my_string.format(**my_args)
'text_with_VAR_1_to_variables_VAR_2'
Use the one which satisfies your requirement. :)
Do you have to use format? If not, can you just use string.replace? like
my_string = 'text_with_#var_1#_to_variables_#var2#'
my_string = my_string.replace("#var_1#", '10')
###
my_string = my_string.replace("#var2#", '22')
following seems to work now.
s = 'a {} {{}}'.format('b')
print(s) # prints a b {}
print(s.format('c')) # prints a b c
Can someone explain me why my regex is not getting satisfied for below regex expression. Could someone let me know how to overcome and check for [] match.
>>> str = li= "a.b.\[c\]"
>>> if re.search(li,str,re.IGNORECASE):
... print("Matched")
...
>>>
>>> str = li= r"a.b.[c]"
>>> if re.search(li,str,re.IGNORECASE):
... print("Matched")
...
>>>
If I remove open and close brackets I get match
>>> str = li= 'a.b.c'
>>> if re.search(li,str,re.IGNORECASE):
... print("matched")
...
matched
You are attempting to match the string a.b.\\[c\\] instead of a.b.[c].
Try this:
import re
li= r"a\.b\.\[c\]"
s = "a.b.[c]"
if re.search(li, s, re.IGNORECASE):
print("Matched")
re.IGNORECASE is not needed in here by the way.
You can try the following code:
import re
str = "a.b.[c]"
if re.search(r".*\[.*\].*", str):
print("Matched")
Output:
Matched
let two strings
s='chayote'
d='aceihkjouty'
the characters in string s is present in d Is there any built-in python function to accomplish this ?
Thanks In advance
Using sets:
>>> set("chayote").issubset("aceihkjouty")
True
Or, equivalently:
>>> set("chayote") <= set("aceihkjouty")
True
I believe you are looking for all and a generator expression:
>>> s='chayote'
>>> d='aceihkjouty'
>>> all(x in d for x in s)
True
>>>
The code will return True if all characters in string s can be found in string d.
Also, if string s contains duplicate characters, it would be more efficient to make it a set using set:
>>> s='chayote'
>>> d='aceihkjouty'
>>> all(x in d for x in set(s))
True
>>>
Try this
for i in s:
if i in d:
print i
I have a 'NoneType' object like:
A='ABC:123'
I would like to get an object keeping only the digits:
A2=digitsof(A)='123'
Split at the colon:
>>> A='ABC:123'
>>> numA = int(A.split(':')[1])
123
How about:
>>> import re
>>> def digitsof(a):
... return [int(x) for x in re.findall('\d+', a) ]
...
>>> digitsof('ABC:123')
[123]
>>> digitsof('ABC:123,123')
[123, 123]
>>>
Regular Expressions?
>>> from re import sub
>>> A = 'ABC:123'
>>> sub(r'\D', '', A)
123
A simple filter function
A='ABC:123'
filter(lambda s: s.isdigit(), A)
I have some Python code that pulls strings out of a text file:
[2.467188005806714e-05, 0.18664554919828535, 0.5026880460053854, ....]
Python code:
v = string[string.index('['):].split(',')
for elem in v:
new_list.append(float(elem))
This gives an error:
ValueError: could not convert string to float: [2.974717463860223e-06
Why can't [2.974717463860223e-06 be converted to a float?
You've still got the [ in front of your "float" which prevents parsing.
Why not use a proper module for that? For example:
>>> a = "[2.467188005806714e-05, 0.18664554919828535, 0.5026880460053854]"
>>> import json
>>> b = json.loads(a)
>>> b
[2.467188005806714e-05, 0.18664554919828535, 0.5026880460053854]
or
>>> import ast
>>> b = ast.literal_eval(a)
>>> b
[2.467188005806714e-05, 0.18664554919828535, 0.5026880460053854]
You may do the following to convert your string that you read from your file to a list of float
>>> instr="[2.467188005806714e-05, 0.18664554919828535, 0.5026880460053854]"
>>> [float(e) for e in instr.strip("[] \n").split(",")]
[2.467188005806714e-05, 0.18664554919828535, 0.5026880460053854]
The reason your code is failing is, you are not stripping of the '[' from the string.
You are capturing the first bracket, change string.index("[") to string.index("[") + 1
This will give you a list of floats without the need for extra imports etc.
s = '[2.467188005806714e-05, 0.18664554919828535, 0.5026880460053854]'
s = s[1:-1]
float_list = [float(n) for n in s.split(',')]
[2.467188005806714e-05, 0.18664554919828535, 0.5026880460053854]
v = string[string.index('[') + 1:].split(',')
index() return index of given character, so that '[' is included in sequence returned by [:].