px.Range

Author: nicolaskruchten

packages/python/plotly/plotly/express/__init__.py

@@ -55,10 +55,7 @@
     get_trendline_results,
 )
 
-from ._special_inputs import (  # noqa: F401
-    IdentityMap,
-    Constant,
-)
+from ._special_inputs import IdentityMap, Constant, Range  # noqa: F401
 
 from . import data, colors  # noqa: F401
 
@@ -102,4 +99,5 @@
     "get_trendline_results",
     "IdentityMap",
     "Constant",
+    "Range",
 ]

packages/python/plotly/plotly/express/_core.py

@@ -1,7 +1,7 @@
 import plotly.graph_objs as go
 import plotly.io as pio
 from collections import namedtuple, OrderedDict
-from ._special_inputs import IdentityMap, Constant
+from ._special_inputs import IdentityMap, Constant, Range
 
 from _plotly_utils.basevalidators import ColorscaleValidator
 from .colors import qualitative, sequential
@@ -961,6 +961,7 @@ def build_dataframe(args, constructor):
             df_output[df_input.columns] = df_input[df_input.columns]
 
     constants = dict()
+    ranges = list()
 
     # Loop over possible arguments
     for field_name in all_attrables:
@@ -993,13 +994,16 @@ def build_dataframe(args, constructor):
                     "pandas MultiIndex is not supported by plotly express "
                     "at the moment." % field
                 )
-            # ----------------- argument is a constant ----------------------
-            if isinstance(argument, Constant):
+            # ----------------- argument is a special value ----------------------
+            if isinstance(argument, Constant) or isinstance(argument, Range):
                 col_name = _check_name_not_reserved(
                     str(argument.label) if argument.label is not None else field,
                     reserved_names,
                 )
-                constants[col_name] = argument.value
+                if isinstance(argument, Constant):
+                    constants[col_name] = argument.value
+                else:
+                    ranges.append(col_name)
             # ----------------- argument is a col name ----------------------
             elif isinstance(argument, str) or isinstance(
                 argument, int
@@ -1087,6 +1091,9 @@ def build_dataframe(args, constructor):
     for col_name in constants:
         df_output[col_name] = constants[col_name]
 
+    for col_name in ranges:
+        df_output[col_name] = range(len(df_output))
+
     if wide_mode:
         # TODO multi-level index
         # TODO multi-level columns

packages/python/plotly/plotly/express/_special_inputs.py

@@ -27,3 +27,14 @@ class Constant(object):
     def __init__(self, value, label=None):
         self.value = value
         self.label = label
+
+
+class Range(object):
+    """
+    Objects of this class can be passed to Plotly Express functions that expect column
+    identifiers or list-like objects to indicate that this attribute should be mapped
+    onto integers starting at 0. An optional label can be provided.
+    """
+
+    def __init__(self, label=None):
+        self.label = label

packages/python/plotly/plotly/tests/test_core/test_px/test_px_input.py

@@ -374,6 +374,21 @@ def test_constants():
     assert fig.layout.legend.title.text == "symbol"
 
 
+def test_ranges():
+    fig = px.scatter(x=px.Range(), y=[1, 2], hover_data=[px.Range()])
+    assert fig.data[0].x[0] == 0
+    assert fig.data[0].x[1] == 1
+    assert fig.data[0].customdata[0][0] == 0
+    assert fig.data[0].customdata[1][0] == 1
+    assert "x=" in fig.data[0].hovertemplate
+
+    fig = px.scatter(x=px.Range(label="time"), y=[1, 2])
+    assert fig.data[0].x[0] == 0
+    assert fig.data[0].x[1] == 1
+    assert "x=" not in fig.data[0].hovertemplate
+    assert "time=" in fig.data[0].hovertemplate
+
+
 def test_auto_orient():
     categorical = ["a", "a", "b", "b"]
     numerical = [1, 2, 3, 4]