1

I am trying to find a minimum value in a dataframe with all column values.

Sample data:

**Fitness Value MSU Locations   MSU Range** 
1.180694        {17, 38, 15}    2.017782    
1.202132        {10, 22, 39}    2.032507    
1.179097        {10, 5, 38}     2.048932    
1.175793        {27, 20, 36}    1.820395    
1.187460        {33, 10, 34}    1.922506

I am trying to find a minimum value in Fitness Value column and keeping the whole row record. For intance, If I get the minimum value (1.175793), I want to keep its respective header values which are {27, 20, 36} and 1.820395. So, the final output should be:

1.175793           {27, 20, 36}      1.820395

My sample code:

minValue = df_2['Fitness Value'].min()
print("minimum value in column 'y': " , minValue)

Output:

minimum value in column 'y':  1.175793

I also tried this code:

df_y = pd.DataFrame ()
df_y = df_2.loc[[df_2['Fitness Value']].min()

How can I get an output like this?

1.175793           {27, 20, 36}      1.820395
Improve this question

3 Answers 3

Reset to default
2

Use min with boolean indexing:

df.loc[df['Fitness Value'].eq(df['Fitness Value'].min())]

Output:

   Fitness Value MSU Locations  MSU Range
3       1.175793  {27, 20, 36}   1.820395

NB. the difference between my answer and that of @jezrael lies in the handling of duplicates in "Fitness Value". Mine keeps all rows with the min, idxmin keeps only the first min. To adapt, depending on what you want.

Improve this answer
Sign up to request clarification or add additional context in comments.

7 Comments

Yes. Your solution is also handling duplicates. it was important to be addressed. Thank you.
@LearningLogic so I'm confused, which one did you need, this one or idxmin?
I am still trying since I am getting duplications. There are similar minimum values in multiple lists after iterations. I need to put only one on my list.
@LearningLogic - If need only one need .idxmin
@LearningLogic I think your goal is still unclear, why don't you update your example to show what is really expected in the real use case
|
2

Use Series.idxmin for indices by minimal values, select row by DataFrame.loc for get row first minimal value in Fitness Value column:

df = df_2.loc[[df_2['Fitness Value'].idxmin()]]
print (df)
   Fitness Value MSU Locations  MSU Range
3       1.175793    {27,20,36}   1.820395

If need list without columns:

L = df_2.loc[df_2['Fitness Value'].idxmin()].tolist()

If need loop:

out = []
for x in range(0, 2, 1): 
    new_generation = genetic_algorithm(initial_pop_chromosome_fitness)   
    initial_pop_chromosome_fitness = new_generation

    #create Series and append to list of Series out
    s = df_2.loc[df_2['Fitness Value'].idxmin()]
    out.append(L)

df = pd.DataFrame(out)
Improve this answer

2 Comments

Comments are not for extended discussion; this conversation has been moved to chat.
Hi @jezrael can you take a quick look at the relevant questions?stackoverflow.com/questions/74548310/…
1

A solution using your minValue variable.

df[df["Fitness Value"]==minValue]
Improve this answer

Comments

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.