How To Plot Error Bars In Xmgrace
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well, its support for bar graphs is rudimentary. In contrast, xmgrace handles bar graphs better, but its menu system is perverse, which makes it quite difficult xmgrace plot to use. Proof that it is possible. This article describes how to create
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a bar graph with error bars in xmgrace, and set each bar to a different fill pattern. In xmgrace, xmgrace symbols this can only be done by loading each data point separately through a procedure that is non-intuitive, to say the least. I wrote this page to avoid having to figure out the
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arcane procedure for doing this every time. Importing data In this simple example, we will have seven bars. Each bar needs three numbers: an x value, a y value, and an error bar value. Create data file in one long row, for example: 1 10.1 0.27 2 1.36 0.49 3 0.42 0.08 \ 4 0.43 0.24 5 0.66 0.22 6 0.11 0.41 \ 7 6.6 xmgrace evaluate expression 2.01 That is, the first bar is 10.1 plus/minus 0.27, and the bars are to be evenly spaced at 1 unit intervals. Although it's broken up here into three lines to fit on my web page, the data should be a single row of numbers in groups of three: x, y, and dy. If you want to bunch some of the bars together, leave larger intervals between some of the x values. Don't open the data file yet. The graph type must be set to "XY chart" before reading the file, otherwise you will be prevented from plotting it as a bar graph. Plot | Graph Appearance Set Presentation Type XY Chart Apply Close Import the first data point from the data file. Data | Import | ASCII Select filename. Load as "block data". (Alternatively, you could load the file as "Single set". This would also create a bar graph, but all the bars would be the same color and pattern. In this case, you should put the data in a conventional format, with the x's, y's, and dy's in three separate columns. However, a bar graph in which all the bars
such as lines and boxes. xmgr uses 3 coordinate systems in drawing a graph. These are the world, viewport, and device coordinate systems (following Foley and Van Dam). The world coordinates system is the one in which the data are defined and constitutes the
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user's coordinate system. The viewport coordinate system (in xmgr), is a rectangle defined by the points
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(0.0, 0.0) or the lower left corner of the device and (1.0, 1.0) or the upper right corner of the device. The pipeline for drawing xmgrace manual objects on the screen or hardcopy device is a pair of linear transformations that carry points in world coordinates to the viewport and then on to the device coordinate system. The upshot is that an object located in world coordinates can http://randombio.com/linuxsetup66.html be drawn in various parts of the screen or hardcopy device depending on the scaling while an object located in viewport coordinates remains in the same spot regardless of the world scaling. Strings, lines, boxes, and the graph legend can be located in either world or viewport coordinates. World scaling Viewport Autoscale Titles Ticks labels/tick marks Frame Symbols Error bars Legends Strings & Things Time stamp World scaling Define the world coordinate system by filling in the items Xmin, Xmax, Ymin, and http://plasma-gate.weizmann.ac.il/Xmgr/doc/plot.html Ymax. The plot is drawn in world coordinates in a rectangle described by the two points (Xmin, Ymin), (Xmax, Ymax). The input is scanned for arithmetic expressions so setting Xmin = -PI and Xmax = PI is legal input (see the section on transformations for a description of the syntax and available functions). The tick spacing can also be set in this popup by filling in the items for the major and minor spacing for each axis. `Update world/ticks' is used, when, occasionally, the state of the items used to define the world scaling get out of sync with what is actually used to draw the graph, clicking on this item synchronizes the internal values with the displayed values. Press the button marked Accept to inform xmgr of the changes. Note: make sure Xmin < Xmax and Ymin < Ymax. Viewport Define the viewport by filling in the items Xmin, Xmax, Ymin, Ymax. Viewport coordinates run from (0.0,0.0), the lower left corner of the screen or hardcopy device, to (1.0,1.0), the upper right corner of the screen or hardcopy device. Press the button marked Accept to make the change to the new viewport. Press the Pick view button to use the mouse to define the viewport. Take the mouse to the lower left corner of the desired viewport and press the left button (there is no need to hold the button down). A rubberband box will show you the current size of the
well, its support for bar graphs is rudimentary. In contrast, xmgrace handles bar graphs better, but its menu system is perverse, which makes it quite difficult to use. Proof that it is possible. This article describes how to create a bar graph with error bars in xmgrace, http://randombio.com/linuxsetup66.html and set each bar to a different fill pattern. In xmgrace, this can only be done by loading each data point separately through a procedure that is non-intuitive, to say the least. I wrote this page to avoid having to figure out the arcane procedure for doing this every time. Importing data In this simple example, we will have seven bars. Each bar needs three numbers: an x value, a y value, and an error bar value. Create data file in one long row, for example: 1 how to 10.1 0.27 2 1.36 0.49 3 0.42 0.08 \ 4 0.43 0.24 5 0.66 0.22 6 0.11 0.41 \ 7 6.6 2.01 That is, the first bar is 10.1 plus/minus 0.27, and the bars are to be evenly spaced at 1 unit intervals. Although it's broken up here into three lines to fit on my web page, the data should be a single row of numbers in groups of three: x, y, and dy. If you want to bunch some of the bars together, leave larger how to plot intervals between some of the x values. Don't open the data file yet. The graph type must be set to "XY chart" before reading the file, otherwise you will be prevented from plotting it as a bar graph. Plot | Graph Appearance Set Presentation Type XY Chart Apply Close Import the first data point from the data file. Data | Import | ASCII Select filename. Load as "block data". (Alternatively, you could load the file as "Single set". This would also create a bar graph, but all the bars would be the same color and pattern. In this case, you should put the data in a conventional format, with the x's, y's, and dy's in three separate columns. However, a bar graph in which all the bars look exactly alike is usually not very useful). The Edit Block Data dialog will open. Set type = BARDY Select columns 1, 2, and 3 for x, y, and y1 for graph number G0. If the graph isn't drawn automatically, click on ^$ to draw the graph. If you still don't see a graph, try setting the xmin and ymin to negative numbers. Sometimes xmgrace puts bars in the wrong place, such as at x=-1. Load the remaining data points To load the next bar, you can't just import the next three columns. You have to define another graph that will be superimposed on the first graph. Edit | Arrange Graphs Matrix ... Rows = Change to 7 Check "Add graphs as needed to fill the matrix" Apply Set the ty
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