R : Loop to keep only one specific value

Question

I have a dataset and I would like to keep the value in a column of this dataframe (test_masses) for the mass having the highest intensity for masses close to the rounding of 2.

I created a loop but by observing the result of the dataframe, I see that this one is not optimal. Especially at values 95 and others

Here is the code:

data_frame = read.csv(file = "/home/julien/Bureau/test/File_Name.csv" )
data_frame$test_masses = 'NaN'

df <-data_frame[order(data_frame$masses),]

for (i in 1:(nrow(df)-1)) {
  
  if( round(df[i,"masses"], digits = 2) == 
           round(df[i+1,"masses"], digits = 2) & df[i,"intensities"] > 
           df[i+1,"intensities"])
      
       {
    
    df[i,'test_masses'] <- df[i,'masses']
    
     }
}

You can find an output of the image too.

Taking the example for this image, I would therefore like the line with the highest intensity (line 6) to be written on the test_masses column

Finally here is the drive link of the dataframe :

https://drive.google.com/file/d/1YpVxD54V1rUyidivyTyF92ssXdHHAPge/view?usp=sharing

Thank you for your answers

Answer 1

Ok i find it guys

    for (i in 1:(nrow(df)-1)) {
  

      if( round(df[i,"masses"], digits = 2) == round(df[i+1,"masses"], digits = 2) & df[i,"intensities"] == df[i+1,"intensities"])
      
       {
    
    df[i+1,'intensities'] <- df[i+1,'intensities'] - 1
    
     }
}

    ok = df %>% group_by(round(masses , digits = 2)) %>% top_n(1, intensities)

    names(ok)[names(ok) == "round(masses, digits = 2)"] <- "rounded"
    ok = ok[!duplicated(ok$rounded),]