world!, I ran into a problem earlier today... I am trying to split operations apart from digits and variables. it'll split ,-,/,* apart from the digits or the variable (ex: 10 11 10 goes in the code and a list comes out with ["10"," ","11"," ","10"])

My code:

x = "100 20 a"

operators = ["*","/"," ","-"]

def get_index_of(OP,txt):
  return [v for v,i in enumerate(txt " ") if i == OP]

l = []
for i in operators:
  l.append(get_index_of(i,x))

spliting = sum(l,[])

out = []
for j in spliting:
  out.append(x)
  x = x[:j]

print(out)

The output I get:

['100 20 a', '100', '100']

The output I want:

["100"," ","20"," ","a"]

CodePudding user response：

Using stack

def parse(expression, operators = ["*","/"," ","-"]):
    stack = ['']               # start with empty string on stack
    for c in expression:
        if c in operators:
            stack.append(c)    # place operator as new element on stack
            stack.append('')
        elif c != " ":         # not a space
            stack[-1]  = c     # append to last element on stack
            
    return stack

Example

print(parse("100 20 a"))
# Output: ['100', ' ', '20', ' ', 'a']

CodePudding user response：

Try:

from itertools import groupby

x = "100 20 a"
operators = {"*", "/", " ", "-"}  # <-- use set instead of a list

out = ["".join(g) for _, g in groupby(x, operators.__contains__)]
print(out)

Prints:

['100', ' ', '20', ' ', 'a']

CodePudding user response：

If you're open to 3rd party tool - there is a simple approach:

It's easy to convert to your desired function.

from more_itertools import split_at

>>>lst = list(split_at(x, lambda x: x == ' ', keep_separator=True))
                       
>>>lst
                       
[['1', '0', '0'], [' '], ['2', '0'], [' '], ['a']]
outs = [''.join(x) for x in lst]
                       
>>>outs
                       
['100', ' ', '20', ' ', 'a']

# or doing in one shot:
>>>final = [''.join(x) for x in split_at(x, lambda x: x == ' ', keep_separator=True)]