Matching key value pair from a python dictionary gives absurd results - python-3.x

Question

I have created a python dictionary for expanding acronyms. For example, the dictionary has the following entry:
Acronym_dict = {
"cont":"continued"
}
The code for the dictionary lookup is as follows:
def code_dictionary(text, dict1=Acronym_dict):
for word in text.split():
for key in Acronym_dict:
if key in text:
text = text.replace(key, Acronym_dict[key],1)
return text
The problem is that the code is replacing every string that contains substring 'cont' with continued. For example, continental is getting replaced by 'continuedinental' by the dictionary. This is something that I don't want. I know I can add space before and after each key in the dictionary but that will be time-consuming as the dictionary is quite long. Any other alternative?? Please suggest.

Answer 1

A few solutions:
Use regular expressions to find isolated words using \b (word break):
import re
Acronym_dict = {
r'\bcont\b':'continued'
}
def code_dictionary(text, dict1=Acronym_dict):
for key,value in dict1.items():
text = re.sub(key,value,text)
return text
s = 'to be cont in continental'
print(code_dictionary(s))
to be continued in continental
If you don't want to change your dictionary, build the regular expression. Note re.escape makes sure the key doesn't contain anything treated differently by a regular expression:
import re
Acronym_dict = {
'cont':'continued'
}
def code_dictionary(text, dict1=Acronym_dict):
for key,value in dict1.items():
regex = r'\b' + re.escape(key) + r'\b'
text = re.sub(regex,value,text)
return text
s = 'to be cont in continental'
print(code_dictionary(s))
to be continued in continental
Fanciest version, does all the acronym replacement in one call to re.sub:
import re
Acronym_dict = {'a':'aaa',
'b':'bbb',
'c':'ccc',
'd':'ddd'}
def code_dictionary(text, dict1=Acronym_dict):
# ORs all the keys together, longest match first.
# E.g. generates r'\b(abc|ab|b)\b'.
# Captures the value it matches.
regex = r'\b(' + '|'.join([re.escape(key)
for key in
sorted(dict1,key=len,reverse=True)]) + r')\b'
# Replace everything in the text in one regex.
# Uses a callback to look up the value of the acronym.
return re.sub(regex,lambda m: dict1[m.group(1)],text)
s = 'a abcd b abcd c abcd d'
print(code_dictionary(s))
aaa abcd bbb abcd ccc abcd ddd

Answer 2

Try this:
import re
Acronym_dict = {
"cont":"continued"
}
def code_dictionary(text, dict1=Acronym_dict):
# for word in text.split():
for key in Acronym_dict:
text = re.sub(r'\b' + key + r'\b', Acronym_dict[key], text)
return text
if __name__ == "__main__":
text = '''
abcd cont ajflkasdfla cont.
cont continental afakjsklfjakl jfalfj asl cont fjdlaskfjal fjal
cont
'''
print(text)
print('--------------------')
print(code_dictionary(text))