title: Seaborn boxplot for classification with pandas wide to long
body: <p>I have data that I would like to train an ml classifier on. The data is in wide format. I'd like to do a boxplot with searborn <code>sns.boxplot(x='variable',y='value', hue='target', data=df_train)</code>. How do I reshape the data to be able to pass it to <code>sns.boxplot</code>?</p>
  <p>Sample data</p>
  <pre><code>import pandas as pd
  from sklearn import datasets
  X, y = datasets.make_classification(n_samples=100, n_features=5, random_state=1)
  df_train = pd.DataFrame(X)
  df_train['y']=y
  </code></pre>