Searching a String inside String in Nested Arrays in Python

Question

I am trying to have a basic function to find a string inside another string in a nested list. But its unable to find the same. Is anything fundamentally wrong ?

import Tkinter, Tkconstants, tkFileDialog
from   Tkinter import *
import subprocess
import ttk
import re

def find_index_sub_string(needle,haystack):
    return [i for i, x in enumerate(haystack) if needle in x]

mc_pool = [['fruit,apple', '1,appl_c', [''], '1,am', '1,as', ['fruit,apple,am-fruit,apple,as-rocky,1'], '/abc/bb/ccc/dd/e', ['1,aa', ['fruit,apple,aa', 'aa', 1, [], [], [], [], [], []]]], ['apple,appl_c', '', [''], '1,mm', '1,ms', ['apple,appl_c,mm-apple,appl_c,ms-rambo,1'], '/aa/bbbd/cc/dddd', ['']]]
mc_pool_cln = [['fruit,apple', '1,appl', ['fruit,apple,mas', 'mas', '5'], '1,am', '1,as', ['fruit,apple,am-fruit,apple,as-rocky,1'], '/abc/bb/ccc/dd/e', ['1,aa', ['fruit,apple,aa', 'aa', 1, [], [], [], [], [], []]]], ['apple,appl', '', [''], '1,mm', '1,ms', ['apple,appl,mm-apple,appl,ms-rambo,1'], '/aa/bbbd/cc/dddd', ['']]]

mc_idx = find_index_sub_string('_c', mc_pool)
print mc_idx 

mc_idx = find_index_sub_string('_c', mc_pool_cln)
print mc_idx

Update:

Have added another array mc_pool_cn which doesn't contain any of the strings i.e. _c..
Was expecting the output like, [[0,1], [1,0], [1,5]].. i.e. like the respective index location of the sub string that appears..

Barmar · Accepted Answer · 2019-11-23 10:22:09Z

1

You're searching for an exact match, not a substring.

And since you have recursively nested lists, you need to use a recursive function to search to any depth.

def match_substring_recursive(needle, haystack):
    if isinstance(haystack, str):
        return needle in haystack
    else:
        return any(match_substring_recursive(needle, x) for x in haystack)

def find_index_sub_string(needle, haystack):
    return [i for i, x in enumerate(haystack) if match_substring_recursive(needle, x)]

answered Nov 23, 2019 at 10:22

Barmar

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9 Comments

Vimo Over a year ago

Thanks for your inputs.. Quick doubt, this basically return the top level index where it exits right? But I was wondering If i can get the exact index where the element exists as well ? For eg, the element exists in array [0], inside that in location [1].. But this recursive process prints only the top level array number right?

Vimo Over a year ago

The recursive function fails if there isn't any string with '_c' in the arrays as "TypeError: 'int' object is not iterable". Is it bcoz you check for str in the recursive process ?

Barmar Over a year ago

@Vimo It assumes everything is either a string or a list of strings.

Barmar Over a year ago

Please edit the question and show the desired result. I thought you just wanted the top-level indexes, since that's what your function returns.

Vimo Over a year ago

Have already update the query with the another array mc_pool_cln which doesn't contain any _c.. And also to print the respective index where the substring exists..

|

Alexandre B. · Accepted Answer · 2019-11-23 10:51:23Z

0

The problem is that there are list and string in the list. You need to distinguish both types.

The function:

def search(needle, haystack):
    # If haystack is string
    if type(haystack) is str and needle in haystack:
        return [haystack]
    # Else (haystack is a list not empty)
    elif type(haystack) is list and len(haystack) > 0:
        # Recursion on first element and others elements on haystack
        return search(needle, haystack[0]) + search(needle, haystack[1:])
    # default value
    return []

mc_pool = [['fruit,apple', '1,appl_c', [''], '1,am', '1,as', ['fruit,apple,am-fruit,apple,as-rocky,1'], '/abc/bb/ccc/dd/e', ['1,aa', ['fruit,apple,aa', 'aa', 1, [], [], [], [], [], []]]], ['apple,appl_c', '', [''], '1,mm', '1,ms', ['apple,appl_c,mm-apple,appl_c,ms-rambo,1'], '/aa/bbbd/cc/dddd', ['']]]
mc_idx = search('_c', mc_pool)

print (mc_idx) 
# ['1,appl_c', 'apple,appl_c', 'apple,appl_c,mm-apple,appl_c,ms-rambo,1']

Hope that helps you.

answered Nov 23, 2019 at 10:51

Alexandre B.

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5 Comments

Vimo Over a year ago

Thanks for your inputs.. But this will be returning the variables as such if it exists right? not the index value.

Alexandre B. Over a year ago

The current code return all string of the list having needle as a sub-string. What is your desired output ?

Vimo Over a year ago

Was mainly trying to return the index of the list which contains the required sub string in the string, not to return the string as a whole..

Alexandre B. Over a year ago

I'm not sure to understand since this is a recursive search. Can you share the expected output on this example ?

Vimo Over a year ago

You are printing that string as such if there is any in the list. But I was trying to print the index where that particular string exists. For eg [0,1] i.e. the string exists in the array 0 in the location 1, something like that..

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