1 files changed, 29 insertions, 0 deletions
diff --git a/chroma/histogram/graph.py b/chroma/histogram/graph.py
new file mode 100644
index 0000000..5e27dee
--- /dev/null
+++ b/chroma/histogram/graph.py
@@ -0,0 +1,29 @@
+import numpy as np
+
+class Graph(object):
+    """
+    Graph object.
+
+    Args:
+        - x: array, *optional*
+        - y: array, *optional*
+        - xerr: array, *optional*
+        - yerr: array, *optional*
+    """
+    def __init__(self, x=[], y=[], xerr=None, yerr=None):
+        self.x = np.asarray(x)
+        self.y = np.asarray(y)
+        if xerr is None:
+            self.xerr = np.zeros(self.x.size)
+        else:
+            self.xerr = np.array(xerr)
+        if yerr is None:
+            self.yerr = np.zeros(self.x.size)
+        else:
+            self.yerr = np.array(yerr)
+
+        if self.y.size != self.x.size or self.xerr.size != self.x.size \
+               or self.yerr.size != self.x.size:
+            raise ValueError('array size mismatch')
+
+        self.size = self.x.size