From ce57e342b13b707ced425c13164be3691b42e501 Mon Sep 17 00:00:00 2001
From: Grant Sanderson <grant@3blue1brown.com>
Date: Sat, 5 May 2018 19:41:30 -0700
Subject: [PATCH] Added break_up_string_by_terms

---
 utils/strings.py | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/utils/strings.py b/utils/strings.py
index fdadf99b..cc4307ac 100644
--- a/utils/strings.py
+++ b/utils/strings.py
@@ -1,5 +1,6 @@
 import re
 import string
+import itertools as it
 
 
 def to_camel_case(name):
@@ -24,3 +25,27 @@ def camel_case_initials(name):
 
 def complex_string(complex_num):
     return filter(lambda c: c not in "()", str(complex_num))
+
+
+def break_up_string_by_terms(full_string, *terms):
+    """
+    Given a string, and an arbitrary number of possible substrings, returns a list
+    of strings which would concatenate to make the full string, and in which
+    these special substrings appear as their own elements.
+
+    For example, break_up_string_by_terms("to be or not to be", "to", "be") would
+    return ["to", " ", "be", " or not ", "to", " ", "be"]
+    """
+    if len(terms) == 0:
+        return [full_string]
+    term = terms[0]
+    substrings = list(it.chain(*zip(
+        full_string.split(term),
+        it.repeat(term)
+    )))
+    substrings.pop(-1)
+    substrings = filter(lambda s: s != "", substrings)
+    return list(it.chain(*[
+        break_up_string_by_terms(substring, *terms[1:])
+        for substring in substrings
+    ]))