added bar chart examples

tikz/bar-chart-grouping/bar-chart-grouping.tex

@@ -0,0 +1,29 @@
+% Source: http://tex.stackexchange.com/a/69234/5645
+\documentclass[varwidth=true, border=2pt]{standalone}
+
+\usepackage{pgfplots}
+
+\begin{document}
+    \begin{tikzpicture}
+        \begin{axis}[
+            ybar,
+            ylabel={vaule/weight},
+            xlabel={items},
+            legend style={at={(0.5,-0.15)},
+            anchor=north,legend columns=-1},
+            width=0.8*\textwidth,
+            height=9cm,
+            bar width=7pt,
+            symbolic x coords={$x_1$,$x_2$,$x_3$,$x_4$,$x_5$},
+            xtick=data,
+            %nodes near coords,
+            %nodes near coords align={vertical},
+        ]
+            \addplot
+            coordinates {($x_1$,96000) ($x_2$,126000) ($x_3$,115000) ($x_4$,125000) ($x_5$,123000)};
+            \addplot
+            coordinates {($x_1$,27) ($x_2$,21) ($x_3$,27)  ($x_4$,15) ($x_5$,19)};
+            \legend{value, weight}
+        \end{axis}
+    \end{tikzpicture}
+\end{document}