title: How to make a correlation heatmap with seaborn but filtering by a specific column?
body: <p>I want to make a correlation heatmap between 2 columns in a df, but filtered by a3 columns.
  I have a DF like this with 3 columns, and I want to make 1 heatmap to each region, but I couldn't find the way to make it.</p>
  
  <pre><code>chldmort    adfert      region
  34.75       7.300000    Africa
  122.75      111.699997  Americas
  60.25       52.099998   Asia
  170.50      124.800003  Europe
  168.50      18.600000   Oceania
  </code></pre>
  
  <p>I try to this in seaborn, but I couldn't get an efficient way to do it for all-region in a row.</p>
  
  <pre><code>tmp=df.loc[:,['chldmort','adfert','region']].dropna()
  tmp_africa=tmp[tmp['region']=='Africa']
  tmp_americas=tmp[tmp['region']=='Americas']
  tmp_asia=tmp[tmp['region']=='Asia']
  tmp_europe=tmp[tmp['region']=='Europe']
  tmp_oceania=tmp[tmp['region']=='Oceania']
  plt.figure(figsize=(20,20))
  plt.subplot(5,1,1)
  plt.title("chldmort over adfert, grouped by Africa",size=15)
  sns.heatmap(tmp_africa.corr(cmap='Reds', annot=True, vmax=.99, vmin=0.60, linewidths=0.9)
  plt.subplot(5,1,2)
  sns.heatmap(tmp_americas.corr(), cmap='Reds', annot=True, vmax=.99, vmin=0.60, linewidths=0.9)
  plt.title("chldmort over adfert, grouped by Americas",size=15)
  plt.subplot(5,1,3)
  plt.title("chldmort over adfert, grouped by Asia",size=15)
  sns.heatmap(tmp_asia.corr(), cmap='Reds', annot=True, vmax=.99, vmin=0.60, linewidths=0.9)
  plt.subplot(5,1,4)
  plt.title("chldmort over adfert, grouped by Europe",size=15)
  sns.heatmap(tmp_europe.corr(), cmap='Reds', annot=True, vmax=.99, vmin=0.60, linewidths=0.9)
  plt.subplot(5,1,5)
  plt.title("chldmort over adfert, grouped by Oceania",size=15)
  sns.heatmap(tmp_oceania.corr(), cmap='Reds', annot=True, vmax=.99, vmin=0.60, linewidths=0.9);
  </code></pre>