title: An error occurs in Pandas Indexing.('A value is trying to be set on a copy of a slice from a DataFrame')
body: <p>I asked you this question because I have a small question about Pandas Indexing.</p>
  <p>this is my data</p>
  <pre><code>df['f5'][:10]
  
  10    98.429899
  97    98.429899
  9     98.429899
  76    98.429899
  98    97.381034
  91    97.381034
  86    97.381034
  71    97.381034
  11    91.297791
  19    91.297791
  </code></pre>
  <p>I want to change the 10 data in the 'f5' column to a specific value without reset_index() (while maintaining the index).</p>
  <pre><code>df['f5'][:10] = 91.29779092  #o
  df.loc[:,'f5'][:10] = 91.29779092 #o
  df[:10]['f5'] = 91.29779092  #x
  df.iloc[:10,]['f5'] = 91.29779092 #x
  </code></pre>
  <p>As you can see, the value of O changed well, but X did not change well, so I wonder why.</p>
  <p>And all of this
  'A value is trying to be set on a copy of a slice from a DataFrame,' warns Pandas.
  So I'm thinking about what indexing Pandas wants, but I can't figure it out in my head.</p>
  <p>After reset_index()-&gt;df.loc[:9,'f5'] , what is the other way to keep the index and not get a panda warning? Thank you.</p>