CDD-2371: Add support for manually setting min and max y-axis range

cms/dynamic_content/cards.py

@@ -159,6 +159,15 @@ class SimplifiedChartWithLink(blocks.StructBlock):
         default="",
         help_text=help_texts.CHART_Y_AXIS_TITLE,
     )
+    y_axis_minimum_value = blocks.IntegerBlock(
+        required=False,
+        default=0,
+        help_text=help_texts.CHART_Y_AXIS_MINIMUM_VALUE,
+    )
+    y_axis_maximum_value = blocks.IntegerBlock(
+        required=False,
+        help_text=help_texts.CHART_Y_AXIS_MAXIMUM_VALUE,
+    )
     chart = SimplifiedChartComponent(
         help_text=help_texts.CHART_BLOCK_FIELD,
         required=True,

cms/dynamic_content/help_texts.py

@@ -220,6 +220,18 @@
 If nothing is provided, `metric value` will be used by default.
 """
 
+CHART_Y_AXIS_MINIMUM_VALUE: str = """
+This field allows you to set the first value in the chart's y-axis range. Please
+note that a value provided here, which is higher than the lowest value in the data will
+be overridden and the value from the dataset will be used.
+"""
+
+CHART_Y_AXIS_MAXIMUM_VALUE: str = """
+This field allows you to set the last value in the chart's y-axis range. Please
+note that a value provided here, which is lower than the highest value in the data will
+be overridden and the value from the dataset will be used. 
+"""
+
 REQUIRED_CHART_Y_AXIS: str = """
 A required choice of what to display along the y-axis of the chart.
 """

metrics/api/serializers/charts.py

@@ -13,6 +13,7 @@
     DEFAULT_Y_AXIS,
     ChartAxisFields,
     ChartTypes,
+    DEFAULT_Y_AXIS_MINIMUM_VAlUE,
 )
 from metrics.domain.models import ChartRequestParams, PlotParameters
 
@@ -116,6 +117,18 @@ class ChartsSerializer(serializers.Serializer):
         default="",
         help_text=help_texts.CHART_Y_AXIS_TITLE,
     )
+    y_axis_minimum_value = serializers.IntegerField(
+        required=False,
+        allow_null=True,
+        help_text=help_texts.CHART_Y_AXIS_MINIMUM_VALUE,
+        default=None,
+    )
+    y_axis_maximum_value = serializers.IntegerField(
+        required=False,
+        allow_null=True,
+        help_text=help_texts.CHART_Y_AXIS_MAXIMUM_VALUE,
+        default=None,
+    )
 
     plots = ChartPlotsListSerializer()
 
@@ -136,6 +149,9 @@ def to_models(self) -> ChartRequestParams:
             y_axis=y_axis,
             x_axis_title=self.data.get("x_axis_title", ""),
             y_axis_title=self.data.get("y_axis_title", ""),
+            y_axis_minimum_value=self.data["y_axis_minimum_value"]
+            or DEFAULT_Y_AXIS_MINIMUM_VAlUE,
+            y_axis_maximum_value=self.data["y_axis_maximum_value"],
         )
 
 

metrics/api/serializers/help_texts.py

@@ -97,6 +97,13 @@
 CHART_Y_AXIS_TITLE: str = """
 An optional title to display along the Y axis of the chart
 """
+CHART_Y_AXIS_MINIMUM_VALUE: str = """
+The value used to start the chart's y_axis Eg: 0 will scale the chart to have a 0 as its lowest value.
+"""
+CHART_Y_AXIS_MAXIMUM_VALUE: str = """
+The value used as the chart's highest y_axis value Eg: providing a higher value than appears in the data will
+rescale the chart to that value 
+"""
 ENCODED_CHARTS_RESPONSE: str = """
 The specified chart in the requested format as a URI encoded string (default format = svg)
 """

metrics/domain/charts/chart_settings.py

@@ -1,13 +1,19 @@
 import datetime
+import logging
 from decimal import Decimal
 
 from metrics.domain.charts import colour_scheme
 from metrics.domain.charts.type_hints import DICT_OF_STR_ONLY
-from metrics.domain.charts.utils import return_formatted_max_y_axis_value
+from metrics.domain.charts.utils import (
+    return_formatted_max_y_axis_value,
+    return_formatted_min_y_axis_value,
+)
 from metrics.domain.common.utils import DEFAULT_CHART_WIDTH, get_last_day_of_month
 from metrics.domain.models import PlotGenerationData
 from metrics.domain.models.plots import ChartGenerationPayload
 
+logger = logging.getLogger(__name__)
+
 
 class ChartSettings:
     narrow_chart_width = DEFAULT_CHART_WIDTH
@@ -24,6 +30,14 @@ def width(self) -> int:
     def height(self) -> int:
         return self._chart_generation_payload.chart_height
 
+    @property
+    def y_axis_minimum_value(self) -> int | None:
+        return self._chart_generation_payload.y_axis_minimum_value
+
+    @property
+    def y_axis_maximum_value(self) -> int | None:
+        return self._chart_generation_payload.y_axis_maximum_value
+
     @staticmethod
     def get_tick_font_config() -> DICT_OF_STR_ONLY:
         return {
@@ -121,6 +135,53 @@ def get_line_with_shaded_section_chart_config(self):
         chart_config["showlegend"] = False
         return chart_config
 
+    def build_line_single_simplified_y_axis_value_params(
+        self,
+    ) -> dict[str, list[str | int | Decimal]]:
+        """Returns a dictionary containing `y-axis` parameter values
+
+        Notes:
+            if a `y_axis_minimum_value` is provided that is higher than the
+            lowest value in the `y_axis_values` list then the min value of
+            `y_axis_values` is used as the lowest number in the y-axis range.
+
+            if a `y_axis_maximum_value` is provided that is lower than the
+            highest value in the `y_axis_values` list then the max value of
+            `y_axis_values` is used as the highest number in the y-axis range.
+
+        Returns:
+            A dictionary containing the y-axis parameters than make up the
+            y-axis ticks and tick values.
+        """
+        plots_data = self.plots_data[0]
+
+        if self.y_axis_minimum_value < min(plots_data.y_axis_values):
+            min_value = self.y_axis_minimum_value
+        else:
+            min_value = min(plots_data.y_axis_values)
+            logger.info(
+                "The minimum value provided was to high, fallen back to the min value in the data"
+            )
+
+        if self.y_axis_maximum_value and (
+            self.y_axis_maximum_value > max(plots_data.y_axis_values)
+        ):
+            max_value = self.y_axis_maximum_value
+        else:
+            max_value = max(plots_data.y_axis_values)
+            logger.info(
+                "The maximum value provided was to low, fallen back to the max value in the data"
+            )
+
+        return {
+            "y_axis_tick_values": [min_value, max_value],
+            "y_axis_tick_text": [
+                return_formatted_min_y_axis_value(y_axis_values=[min_value]),
+                return_formatted_max_y_axis_value(y_axis_values=[max_value]),
+            ],
+            "range": [min_value, max_value],
+        }
+
     def build_line_single_simplified_axis_params(
         self,
     ) -> dict[str, list[str | int | Decimal]]:
@@ -130,6 +191,9 @@ def build_line_single_simplified_axis_params(
             dictionary of parameters for charts settings parameters
         """
         plot_data = self.plots_data[0]
+
+        y_axis_params = self.build_line_single_simplified_y_axis_value_params()
+
         return {
             "x_axis_tick_values": [
                 plot_data.x_axis_values[0],
@@ -139,13 +203,12 @@ def build_line_single_simplified_axis_params(
                 plot_data.x_axis_values[0].strftime("%b, %Y"),
                 plot_data.x_axis_values[-1].strftime("%b, %Y"),
             ],
-            "y_axis_tick_values": [0, max(plot_data.y_axis_values)],
-            "y_axis_tick_text": [
-                "0",
-                return_formatted_max_y_axis_value(
-                    y_axis_values=plot_data.y_axis_values,
-                ),
-            ],
+            "y_axis_tick_values": y_axis_params["y_axis_tick_values"],
+            "y_axis_tick_text": y_axis_params["y_axis_tick_text"],
+            "range": y_axis_params["range"],
+            "rangemode": (
+                "tozero" if y_axis_params["y_axis_tick_values"][0] == 0 else "normal"
+            ),
         }
 
     def get_line_single_simplified_chart_config(self):
@@ -178,6 +241,8 @@ def get_line_single_simplified_chart_config(self):
         chart_config["yaxis"]["tickfont"][
             "color"
         ] = colour_scheme.RGBAColours.LS_DARK_GREY.stringified
+        chart_config["yaxis"]["range"] = axis_params["range"]
+        chart_config["yaxis"]["rangemode"] = axis_params["rangemode"]
 
         return chart_config
 

metrics/domain/charts/utils.py

@@ -73,3 +73,44 @@ def return_formatted_max_y_axis_value(
     """
     max_value = _extract_max_value(y_axis_values=y_axis_values)
     return convert_large_numbers_to_short_text(number=max_value)
+
+
+def _extract_min_value(
+    y_axis_values: list[Decimal],
+) -> int:
+    """Extracts the lowest `Decimal` value from the `y_axis_values`
+        list and returns an `Int` rounded to the nearest large number
+
+    Notes:
+        `place_value` is the place of the first digit in the number
+        represented by the number of digits to its right.
+        Eg: a number of `1000` has 3 places afer the first digit
+        so `place_value` of = 3
+
+    Args:
+        y_axis_values: list of Decimal values
+
+    Returns:
+        An integer of the highest value from the list rounded to the
+        nearest 10, 100, 1000, ... depending on the number provided.
+    """
+    min_y_axis_value = round(min(y_axis_values))
+    place_value = len(str(min_y_axis_value)) - 1
+    return round(min_y_axis_value, -place_value)
+
+
+def return_formatted_min_y_axis_value(
+    y_axis_values: list[Decimal],
+) -> int:
+    """Returns the lowest value from `y_axis_values` as a formatted string
+
+    Args:
+        y_axis_values: A list of `Decimal` values representing
+        the y_axis values of a `Timeseries` chart.
+
+    Returns:
+        A string of the lowest  value from `y_axis_values` rounded up
+        and formatted as a short string Eg: 1400 becomes 1k
+    """
+    min_value = _extract_min_value(y_axis_values=y_axis_values)
+    return convert_large_numbers_to_short_text(number=min_value)

metrics/domain/common/utils.py

@@ -124,6 +124,7 @@ def get_y_axis_value(cls, *, name: str) -> str:
 
 DEFAULT_X_AXIS = ChartAxisFields.get_default_x_axis().name
 DEFAULT_Y_AXIS = ChartAxisFields.get_default_y_axis().name
+DEFAULT_Y_AXIS_MINIMUM_VAlUE = 0
 
 
 class DataSourceFileType(Enum):

metrics/domain/models/plots.py

@@ -162,6 +162,8 @@ class ChartRequestParams(BaseModel):
     x_axis_title: str = ""
     y_axis: str
     y_axis_title: str = ""
+    y_axis_minimum_value: int = 0
+    y_axis_maximum_value: int | None = None
 
 
 class NoReportingDelayPeriodFoundError(Exception): ...
@@ -242,6 +244,8 @@ class ChartGenerationPayload(BaseModel):
     chart_height: int
     x_axis_title: str
     y_axis_title: str
+    y_axis_minimum_value: int = 0
+    y_axis_maximum_value: int | None = None
 
 
 class CompletePlotData(BaseModel):

metrics/interfaces/charts/access.py

@@ -321,6 +321,8 @@ def build_chart_generation_payload(self) -> ChartGenerationPayload:
             y_axis_title=self.chart_request_params.y_axis_title,
             chart_height=self.chart_request_params.chart_height,
             chart_width=self.chart_request_params.chart_width,
+            y_axis_minimum_value=self.chart_request_params.y_axis_minimum_value,
+            y_axis_maximum_value=self.chart_request_params.y_axis_maximum_value,
         )
 
     def _build_chart_plots_data(self) -> list[PlotGenerationData]:

tests/integration/metrics/domain/charts/bar/test_generation.py

@@ -49,6 +49,8 @@ def test_main_layout(self, fake_plot_data: PlotGenerationData):
             plots=chart_plots_data,
             x_axis_title="",
             y_axis_title="",
+            y_axis_minimum_value=0,
+            y_axis_maximum_value=None,
         )
 
         # When
@@ -87,6 +89,8 @@ def test_main_bar_plot(self, fake_plot_data: PlotGenerationData):
             plots=chart_plots_data,
             x_axis_title="",
             y_axis_title="",
+            y_axis_minimum_value=0,
+            y_axis_maximum_value=None,
         )
 
         # When
@@ -166,6 +170,8 @@ def test_x_axis_type_is_not_date(self, fake_plot_data: PlotGenerationData):
             plots=chart_plots_data,
             x_axis_title="",
             y_axis_title="",
+            y_axis_minimum_value=0,
+            y_axis_maximum_value=None,
         )
 
         # When

tests/unit/metrics/api/serializers/test_charts.py

@@ -587,6 +587,8 @@ def test_x_and_y_axis_are_none_into_model(
             "plots": chart_plots,
             "x_axis": None,
             "y_axis": None,
+            "y_axis_minimum_value": 0,
+            "y_axis_maximum_value": None,
         }
         serializer = ChartsSerializer(data=valid_data_payload)
 
@@ -621,6 +623,8 @@ def test_to_models_returns_correct_models(self):
             "chart_height": 300,
             "chart_width": 400,
             "plots": chart_plots,
+            "y_axis_minimum_value": 0,
+            "y_axis_maximum_value": None,
         }
         serializer = ChartsSerializer(data=valid_data_payload)
 
@@ -668,6 +672,8 @@ def test_valid_payload_with_optional_x_and_y_fields_provided(self):
             "plots": chart_plots,
             "x_axis": x_axis,
             "y_axis": y_axis,
+            "y_axis_minimum_value": 0,
+            "y_axis_maximum_value": None,
         }
         serializer = ChartsSerializer(data=valid_data_payload)