How to search for substrings in a long string and create a list in Python?

Question

I have a long string:

query = "PREFIX pht: <http://datalab.rwth-aachen.de/vocab/pht/>
         PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 

         SELECT ?Age, ?SexTypes, ?Chest_Pain_Type, ?trestbpsD, ?cholD, 
                    ?Fasting_Glucose_Level, ?Resting_ECG_Type, ?thalachD, 
                    ?Exercise_Induced_Angina, ?oldpeakD, ?caD, ?Slope, ?Thallium_Scintigraphy, ?Diagnosis
                      WHERE {?URI a sct:125676002. }"

Now I need to create a list consisting all the substrings that start with '?'. So the list should look like as follows:

schema = ['Age', 'Sex', 'Chest_Pain_Type', 'Trestbps', 'Chol', 'Fasting_Glucose_Level', 'Resting_ECG_Type', 'ThalachD', 
             'Exercise_Induced_Angina', 'OldpeakD', 'CaD', 'Slope', 'Thallium_Scintigraphy', 'Diagnosis']

I tried with str.startswith(str, beg=0,end=len(string))

But it's not working as I expected. How can do it in Python?

vbar, nice catch! Actually, I don't need the ?URI. I wanted to explain but later on thought it will increase the complexity of the question. — Martin
– Martin, Commented Mar 20, 2018 at 11:12
Yes, it rather does increase the complexity... :-) Regular expression can find all words starting with '?' (see below), but if you want to skip some of them depending on a larger context, you'll need some more steps... — vbar
– vbar, Commented Mar 20, 2018 at 11:29

Rakesh · Accepted Answer · 2018-03-20 10:50:47Z

5

Using regex:

import re
query = """PREFIX pht: <http://datalab.rwth-aachen.de/vocab/pht/>
         PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 

         SELECT ?Age, ?SexTypes, ?Chest_Pain_Type, ?trestbpsD, ?cholD, 
                    ?Fasting_Glucose_Level, ?Resting_ECG_Type, ?thalachD, 
                    ?Exercise_Induced_Angina, ?oldpeakD, ?caD, ?Slope, ?Thallium_Scintigraphy, ?Diagnosis
                      WHERE {?URI a sct:125676002. }"""

#print re.findall("\?\w+", query)
print([i.replace("?", "") for i in re.findall("\?\w+", query)])

Output:

['Age', 'SexTypes', 'Chest_Pain_Type', 'trestbpsD', 'cholD', 'Fasting_Glucose_Level', 'Resting_ECG_Type', 'thalachD', 'Exercise_Induced_Angina', 'oldpeakD', 'caD', 'Slope', 'Thallium_Scintigraphy', 'Diagnosis', 'URI']

answered Mar 20, 2018 at 10:50

Rakesh

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4 Comments

Martin Over a year ago

thanks so much for saving my day! Sorry to bug but what if I want all the occurrences before the 'WHERE'? Can we somehow limit this? I am pretty new to Python.

Rakesh Over a year ago

Sure. You can trim the query string to exclude content after 'WHERE'. Ex: query = query[:query.find("WHERE")]

Martin Over a year ago

Hi Rakesh, that worked perfectly! I already accepted the answer but since I don't have enough reputation so probably is not getting reflected.

Martin Over a year ago

Sorry, I now did! I'm pretty new to StackOverflow too. Thanks :)

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