docs: def _pathogenSamplePlot(self, pathogenName, sampleNames, ax):
          """
          Make an image of a graph giving pathogen read count (Y axis) versus
          sample id (X axis).
  
          @param pathogenName: A C{str} pathogen name.
          @param sampleNames: A sorted C{list} of sample names.
          @param ax: A matplotlib C{axes} instance.
          """
          readCounts = []
          for i, sampleName in enumerate(sampleNames):
              try:
                  readCount = self.pathogenNames[pathogenName][sampleName][
                      'uniqueReadCount']
              except KeyError:
                  readCount = 0
              readCounts.append(readCount)
  
          highlight = 'r'
          normal = 'gray'
          sdMultiple = 2.5
          minReadsForHighlighting = 10
          highlighted = []
  
          if len(readCounts) == 1:
              if readCounts[0] > minReadsForHighlighting:
                  color = [highlight]
                  highlighted.append(sampleNames[0])
              else:
                  color = [normal]
          else:
              mean = np.mean(readCounts)
              sd = np.std(readCounts)
              color = []
              for readCount, sampleName in zip(readCounts, sampleNames):
                  if (readCount > (sdMultiple * sd) + mean and
                          readCount >= minReadsForHighlighting):
                      color.append(highlight)
                      highlighted.append(sampleName)
                  else:
                      color.append(normal)
  
          nSamples = len(sampleNames)
          x = np.arange(nSamples)
          yMin = np.zeros(nSamples)
          ax.set_xticks([])
          ax.set_xlim((-0.5, nSamples - 0.5))
          ax.vlines(x, yMin, readCounts, color=color)
          if highlighted:
              title = '%s\nIn red: %s' % (
                  pathogenName, fill(', '.join(highlighted), 50))
          else:
              # Add a newline to keep the first line of each title at the
              # same place as those titles that have an "In red:" second
              # line.
              title = pathogenName + '\n'
  
          ax.set_title(title, fontsize=10)
          ax.tick_params(axis='both', which='major', labelsize=8)
          ax.tick_params(axis='both', which='minor', labelsize=6)