Merge pull request #344 from scikit-hep/issue336

Fix append method of TTree

tests/test_write.py

@@ -1887,3 +1887,18 @@ def test_issue340(tmp_path):
     t = uproot.open(filename)["t"]
     for i in range(10):
         assert t["normal"].basket(0)[i] == a[i]
+
+def test_basket_append(tmp_path):
+    filename = join(str(tmp_path), "example.root")
+
+    b = newbranch("int32")
+    branchdict = {"intBranch": b}
+    tree = newtree(branchdict)
+    with uproot.recreate(filename, compression=None) as f:
+        f["t"] = tree
+        f["t"].append({"intBranch": 1})
+
+    f = ROOT.TFile.Open(filename)
+    tree = f.Get("t")
+    treedata = tree.AsMatrix().astype(">i4")
+    assert treedata[0] == 1

uproot/write/objects/TTree.py

@@ -121,10 +121,10 @@ def extend(self, branchdict, flush=True):
                         self._branches[key]._branch.treecheck = 0
 
     def append(self, branchdict):
-        for value in branchdict.values:
-            if len(value) != 1:
-                raise Exception("The length of all the baskets should be 1")
-        self.extend(branchdict, flush=False)
+        appenddict = {}
+        for key, value in branchdict.items():
+            appenddict[key] = [value]
+        self.extend(appenddict, flush=False)
 
     def flush(self):
         for key in self._branches.keys():