feat: implement TGraph-writing

src/uproot/__init__.py

@@ -125,7 +125,7 @@
 from uproot.writing import to_writable
 from uproot.writing import dask_write
 
-from uproot.writing.interpret import to_TGraph
+from uproot.writing.interpret import as_TGraph
 
 import uproot.models.TObject
 import uproot.models.TString

src/uproot/writing/interpret.py

@@ -1,11 +1,13 @@
 from __future__ import annotations
 
-import numpy
+import numbers
+
+import numpy as np
 
 import uproot
 
 
-def _to_TGraph(
+def _as_TGraph(
     x,
     y,
     x_errors=None,
@@ -75,21 +77,21 @@ def _to_TGraph(
     # Detecting which type of TGraph to chose
     if any(sym_errors_bool):
         if not all(sym_errors_bool):
-            raise ValueError("Have to specify both x_errors and y_errors")
+            raise ValueError("uproot.as_TGraph requires both x_errors and y_errors")
         if any(asym_errors_bool):
             raise ValueError(
-                "Can's specify both symetrical errors and asymetrical errors"
+                "uproot.as_TGraph can accept symmetrical errors OR asymmetrical errors, but not both"
             )
         tgraph_type = "TGraphErrors"
 
     elif any(asym_errors_bool):
         if not all(asym_errors_bool):
             raise ValueError(
-                "Have to specify all: x_errors_low, x_errors_high, y_errors_low, y_errors_high"
+                "uproot.as_TGraph requires all of the following: x_errors_low, x_errors_high, y_errors_low, y_errors_high"
             )
         if any(sym_errors_bool):
             raise ValueError(
-                "Can's specify both symetrical errors and asymetrical errors"
+                "uproot.as_TGraph can accept symmetrical errors OR asymmetrical errors, but not both"
             )
         tgraph_type = "TGraphAsymmErrors"
 
@@ -130,23 +132,23 @@ def _to_TGraph(
     if len(x) != len(y):
         raise ValueError("Arrays x and y must have the same length!")
     if len(x) == 0:
-        raise ValueError("Arguments and values arrays can't be emty")
+        raise ValueError("x and Y arrays can't be emty")
     if len(x.shape) != 1:
         raise ValueError(f"x has to be 1D, but is {len(x.shape)}D!")
     if len(y.shape) != 1:
         raise ValueError(f"y has to be 1D, but is {len(y.shape)}D!")
 
     if minY is None:
-        new_minY = min(x, default=0)
-    elif not isinstance(minY, (int, float)):
-        raise ValueError(f"fMinium has to be None or a number! But is {type(minY)}")
+        new_minY = np.min(x)
+    elif not isinstance(minY, numbers.Real):
+        raise ValueError(f"minY has to be None or a number! But is {type(minY)}")
     else:
         new_minY = minY
 
     if maxY is None:
-        new_maxY = max(x, default=0)
-    elif not isinstance(maxY, (int, float)):
-        raise ValueError(f"fMinium has to be None or a number! But is {type(maxY)}")
+        new_maxY = np.max(x)
+    elif not isinstance(maxY, numbers.Real):
+        raise ValueError(f"minY has to be None or a number! But is {type(maxY)}")
     else:
         new_maxY = maxY
 
@@ -203,7 +205,7 @@ def _to_TGraph(
     return returned_TGraph
 
 
-def to_TGraph(
+def as_TGraph(
     df,
     title="",
     xAxisLabel="",
@@ -252,36 +254,36 @@ def to_TGraph(
     Also can't specify {x_errors, y_errors} and {x_errors_low, x_errors_high, y_errors_low, y_errors_high} at the same time.
     """
 
-    x = numpy.array(df["x"]) if df.get("x", None) is not None else None
-    y = numpy.array(df["y"]) if df.get("y", None) is not None else None
+    x = np.array(df["x"]) if df.get("x", None) is not None else None
+    y = np.array(df["y"]) if df.get("y", None) is not None else None
     x_errors = (
-        numpy.array(df["x_errors"]) if df.get("x_errors", None) is not None else None
+        np.array(df["x_errors"]) if df.get("x_errors", None) is not None else None
     )
     y_errors = (
-        numpy.array(df["y_errors"]) if df.get("y_errors", None) is not None else None
+        np.array(df["y_errors"]) if df.get("y_errors", None) is not None else None
     )
     x_errors_low = (
-        numpy.array(df["x_errors_low"])
+        np.array(df["x_errors_low"])
         if df.get("x_errors_low", None) is not None
         else None
     )
     x_errors_high = (
-        numpy.array(df["x_errors_high"])
+        np.array(df["x_errors_high"])
         if df.get("x_errors_high", None) is not None
         else None
     )
     y_errors_low = (
-        numpy.array(df["y_errors_low"])
+        np.array(df["y_errors_low"])
         if df.get("y_errors_low", None) is not None
         else None
     )
     y_errors_high = (
-        numpy.array(df["y_errors_high"])
+        np.array(df["y_errors_high"])
         if df.get("y_errors_high", None) is not None
         else None
     )
 
-    return _to_TGraph(
+    return _as_TGraph(
         x,
         y,
         x_errors,

tests/test_1128_TGraph_writing.py

@@ -1,11 +1,14 @@
-import uproot
+# BSD 3-Clause License; see https://github.com/scikit-hep/uproot5/blob/main/LICENSE
+
 import os
-import pandas as pd
+
 import pytest
-import ROOT
 import numpy as np
 
-EPS = 1e-6
+import uproot
+
+pd = pytest.importorskip("pandas")
+ROOT = pytest.importorskip("ROOT")
 
 
 def test_saving_TGraph_to_file(tmp_path):
@@ -15,7 +18,7 @@ def test_saving_TGraph_to_file(tmp_path):
     df = pd.DataFrame({"x": x, "y": y})
 
     with uproot.recreate(newfile) as f:
-        f["myTGraph"] = uproot.to_TGraph(df)
+        f["myTGraph"] = uproot.as_TGraph(df)
 
     with uproot.open(newfile) as f:
         tgraph = f["myTGraph"]
@@ -24,8 +27,8 @@ def test_saving_TGraph_to_file(tmp_path):
         y_new = tgraph.values("y")
 
         for i in range(len(x)):
-            assert abs(x_new[i] - x[i]) < EPS
-            assert abs(y_new[i] - y[i]) < EPS
+            assert x_new[i] == pytest.approx(x[i])
+            assert y_new[i] == pytest.approx(y[i])
 
 
 def test_opening_TGraph_with_root(tmp_path):
@@ -39,7 +42,7 @@ def test_opening_TGraph_with_root(tmp_path):
     yLabel = "yLabel"
 
     with uproot.recreate(newfile) as f:
-        f[tGraphName] = uproot.to_TGraph(
+        f[tGraphName] = uproot.as_TGraph(
             df, title=title, xAxisLabel=xLabel, yAxisLabel=yLabel
         )
 
@@ -53,5 +56,5 @@ def test_opening_TGraph_with_root(tmp_path):
         for i in range(len(x)):
             xAxis = tgraph.GetX()
             yAxis = tgraph.GetY()
-            assert abs(xAxis[i] - x[i]) < EPS
-            assert abs(yAxis[i] - y[i]) < EPS
+            assert xAxis[i] == pytest.approx(x[i])
+            assert yAxis[i] == pytest.approx(y[i])