title: How to copy pandas value to another sheet cell?
body: <p>How could I copy a cell value from one sheet (currently a float) to another sheet that has a blank cell (NaN)?  Below are the steps I've tried.</p>
  
  <p><strong>For Example;</strong> I have this value (510.0):</p>
  
  <pre><code>&gt;&gt;&gt; parcel_csv[parcel_csv.PID == '570-177736'].LANDUSE
  341817    510.0
  Name: LANDUSE, dtype: float64
  </code></pre>
  
  <p>I want it to be assigned here:  </p>
  
  <pre><code>&gt;&gt;&gt; df.loc[df['Parcel ID']=='570-177736',['Land Use']]
  Land Use
  0      NaN
  </code></pre>
  
  <p>Based on other questions, this should work:</p>
  
  <pre><code>&gt;&gt;&gt; df.loc[df['Parcel ID']=='570-177736',['Land Use']] = parcel_csv[parcel_csv.PID == '570-177736'].LANDUSE
  </code></pre>
  
  <p>I still seem to end up with NaN.  So I tried assigning a value first:</p>
  
  <pre><code>&gt;&gt;&gt; df.loc[df['Parcel ID']=='570-177736',['Land Use']] = '111.0'
  &gt;&gt;&gt; df.loc[df['Parcel ID']=='570-177736',['Land Use']]
    Land Use
  0    111.0
  </code></pre>
  
  <p>Tried the 'copy' again:</p>
  
  <pre><code>    &gt;&gt;&gt; df.loc[df['Parcel ID']=='570-177736',['Land Use']] = parcel_csv[parcel_csv.PID == '570-177736'].LANDUSE
  </code></pre>
  
  <p>and ended up with NaN again:</p>
  
  <pre><code>&gt;&gt;&gt; df.loc[df['Parcel ID']=='570-177736',['Land Use']]
    Land Use
  0      NaN
  </code></pre>
  
  <p>Using .loc on the source cell results in the same thing:</p>
  
  <pre><code>&gt;&gt;&gt; parcel_csv.loc[parcel_csv.PID == '570-177736'].LANDUSE
  341817    510.0
  Name: LANDUSE, dtype: float64
  &gt;&gt;&gt; df.loc[df['Parcel ID']=='570-177736',['Land Use']] = parcel_csv.loc[parcel_csv.PID == '570-177736'].LANDUSE
  &gt;&gt;&gt; df.loc[df['Parcel ID']=='570-177736',['Land Use']]
    Land Use
  0      NaN
  </code></pre>
  
  <ol>
  <li>Why can't I copy the value over?   </li>
  <li>Why is the 'Name' and 'dtype' not
  being displayed in the 'destination cell?'  Is that info important?</li>
  </ol>
  
  <p>Python 3.6.7</p>
  
  <p>Thank you!</p>