feat: make contingency table cell size flexible by default (#189)

Resolves #55

edvart/report_sections/bivariate_analysis.py

@@ -1,6 +1,6 @@
 import itertools
 from enum import IntEnum
-from typing import Any, Callable, Dict, List, Optional, Tuple, Union
+from typing import Any, Callable, Dict, List, Literal, Optional, Tuple, Union
 
 import matplotlib.pyplot as plt
 import nbformat.v4 as nbfv4
@@ -792,6 +792,7 @@ def required_imports(self) -> List[str]:
             "from edvart import utils",
             "import seaborn as sns",
             "import matplotlib.pyplot as plt",
+            "from typing import Literal",
         ]
 
     def add_cells(self, cells: List[Dict[str, Any]], df: pd.DataFrame) -> None:
@@ -927,7 +928,7 @@ def contingency_table(
     hide_zeros: bool = True,
     scaling_func: Callable[[np.ndarray], np.ndarray] = np.cbrt,
     colormap: Any = "Blues",
-    size_factor: float = 0.7,
+    size_factor: Union[float, Literal["auto"]] = "auto",
     fontsize: float = 15,
 ) -> None:
     """
@@ -950,8 +951,9 @@ def contingency_table(
         Cube root is used by default.
     colormap : Any (default = "Blues")
         Colormap compatible with matplotlib/seaborn.
-    size_factor : float (default = 0.7)
+    size_factor : float or "auto"
         Size of each cell in the table.
+        If "auto", the cell size is automatically adjusted so that the numbers fit in the cells.
     fontsize : float (default = 15)
         Size of the font for axis labels.
     """
@@ -980,6 +982,13 @@ def contingency_table(
         annot_kws={"fontsize": fontsize},
         square=True,
     )
+    if size_factor == "auto":
+        n_digits_max = 1 + np.floor(np.log10(table.max().max()))
+        # Constants chosen empirically to make the numbers fit in the cells
+        size_factor = max(
+            0.72,
+            0.18 * n_digits_max,
+        )
     ax.figure.set_size_inches(size_factor * len(table.columns), size_factor * len(table))
     # Set y axis
     ax.set_ylabel(ax.get_ylabel(), fontsize=fontsize)