problems with dictionary issue in python code

Question

My Data Science professor posted some code that we are supposed to follow for homework. Here are part of it:

def create_compare_df() -> pd.DataFrame: 
 """Generate comparison dataframe for lists. 
   Returns 
 -------- 
 pd.Dataframe 
 Pandas data frame containing time metrics for selection sort algorithm  -------- 
 """ 
  
 compare: dict = { 
 "array_length" : [512, 1024, 2048, 4096, 8192], 
 "sorted_time": [], 
 "binarysearch_time": [], 
 "linearsearch_time": [], 
 } 
  
 for i in compare["array_length"]: 
.........

I do not know what is the "Compare: dict = ..." part, and wehn I tested the code, it says "compare" is not defined...

I have never seen dictionary defined as above. any idea?

Thanks, Philip

This is a type annotation used poorly. Your code should work if you remove : dict. — erip
– erip, Commented Jul 1, 2021 at 16:44
I tried that and just did a "print(compare)" and got the error saying "NameError: name 'compare' is not defined". — Philip Shangguan
– Philip Shangguan, Commented Jul 1, 2021 at 16:49
You must have typed something wrong. If you wrote compare = { ... } that should define the variable. — Barmar
– Barmar, Commented Jul 1, 2021 at 16:53
Is your print(compare) inside the function? The variable is local, so you can't print it outside the function. — Barmar
– Barmar, Commented Jul 1, 2021 at 16:53
Make sure you copied the indentation correctly. This is why we recommend 4 spaces of indentation, so it's easily visible. — Barmar
– Barmar, Commented Jul 1, 2021 at 16:54

Akshay Saambram · Accepted Answer · 2021-07-01 20:09:48Z

1

compare is a variable name given to it! Your code may work if you go as follows...

compare = { 
    "array_length" : [512, 1024, 2048, 4096, 8192], 
    "sorted_time": [], 
    "binarysearch_time": [], 
    "linearsearch_time": [] 
}

edited Jul 1, 2021 at 20:09

answered Jul 1, 2021 at 16:57

Akshay Saambram

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2 Comments

Philip Shangguan Over a year ago

Thanks it works. I got another problem with the code and that will be another question.

erip Over a year ago

: dict is nothing like type casting. :-)

Bag · Accepted Answer · 2021-07-01 17:00:39Z

1

I would remove the dict = {} part of the equation as it could be used for refrencing. What I would do is the following:

 def create_compare_df() -> pd.DataFrame: 
     """Generate comparison dataframe for lists. 
       Returns 
     -------- 
     pd.Dataframe 
     Pandas data frame containing time metrics for selection sort algorithm  -------- 
 """ 
  
     compare = { 
     "array_length" : [512, 1024, 2048, 4096, 8192], 
     "sorted_time": [], 
    "binarysearch_time": [], 
    "linearsearch_time": [], 
    } 
  
    print(compare)

Basically, you have to be careful with your indentation. So make sure there is a tab in the lines after def.

Let me know if the problem still pertains.

answered Jul 1, 2021 at 17:00

Bag

756 bronze badges

2 Comments

Philip Shangguan Over a year ago

Thanks it works. I got another problem with the code and that will be another question.

Bag Over a year ago

No problem. Happy to help

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