title: Plot Confusion Matrix with scikit-learn without a Classifier
body: <p>I have a confusion matrix created with <code>sklearn.metrics.confusion_matrix</code>.</p>
  <p>Now, I would like to plot it with <code>sklearn.metrics.plot_confusion_matrix</code>, but the first parameter is the trained classifier, as specified in the <a href="https://scikit-learn.org/stable/modules/generated/sklearn.metrics.plot_confusion_matrix.html#sklearn.metrics.plot_confusion_matrix" rel="noreferrer">documentation</a>. The problem is that I don't have a classifier; the results were obtained doing manual calculations.</p>
  <p>Is it still possible to plot the confusion matrix in one line via scikit-learn, or do I have to code it myself with matplotlib?</p>