code: def test_subplot_titles_numeric_square_layout(self, iris):
      df = iris.drop("Name", axis=1).head()
      # Use the column names as the subplot titles
      title = list(df.columns)
      # Case df with 3 numeric columns but layout of (2,2)
      plot = df.drop("SepalWidth", axis=1).plot(
          subplots=True, layout=(2, 2), title=title[:-1]
      )
      title_list = [
          ax.get_title() for sublist in plot for ax in sublist
      ]
      assert title_list == title[:3] + [""]
  
imports: import os
  import numpy
  import pytest
  import pandas.util._test_decorators
  from pandas import DataFrame, Index, Series, Timestamp, date_range, interval_range, period_range, plotting, read_csv
  import pandas._testing
  from pandas.tests.plotting.common import _check_colors, _check_legend_labels, _check_plot_works, _check_text_labels, _check_ticks_props
label_desc: Use image node_id 20 for calling the TestDataFramePlots obj's underlying member method code with example usage: obj.test_subplot_titles_numeric_square_layout(iris) without return types