Creating a Frequency Histogram for a Column of P-Data Values

RockWorks | Borehole Manager | P-Data | Histogram

This program is used to read a single column of P-Data values from all enabled boreholes and determine the frequency or percentage of the total number of measurements for that variable that falls in each user-defined grouping or "cell."  These values are represented as a bar histogram plot. This is the same tool as in the Utilities | Statistics | Histogram | Single menu.

! This frequency histogram will represent your observed borehole measurements.  Should you wish to create a frequency histogram for the nodes in an interpolated model, use the Solid | Statistics | Histogram tool.

Feature Level: RockWorks Standard and higher

Menu Options
Step-by-Step Summary
 

Menu Options

• P-Data Track: Click to the right to select the name of the P-Data column containing the data you wish to process.  Expand this heading to establish any spatial or value filters to apply to the data before running the statistics and generating the diagram.
  • Spatial (XYZ) Filtering: Insert a check in this box to activate a data filter based on spatial coordinates. Expand this heading to establish the filter settings. 
  • Filter Based on G-Values: Activate this option to filter the data based on the measured values, and expand the heading to establish the filter parameters.  (More.)
  • Resample at Regularly-Spaced Intervals: Check this box to resample the data.  (More.)
  • Create Filter / Sampling Report: If you've selected any filter/resampling options, this tool will create a summary report of the results. (More.)
     
• Titles:  Expand this heading, if necessary, to enter diagram titles.
• • Primary:  Click on this item to enter the text to be plotted as the primary title at the top of the histogram plot. The text should be limited to 60 characters. Expand this item to set font type, size (as a percent of the diagram width), color and angle.  If no title is desired, click on this item and delete any text displayed in the prompt.
  • Secondary: Enter the text to be plotted as the secondary title beneath the primary title at the top of the histogram plot. The text should be limited to 60 characters. Expand this item to set font type, color,  size (as a percent of the diagram width), and angle.  If no title is desired, click on this item and delete any text displayed in the prompt.
     
• Scaling & Bin Size: Expand this to choose Linear or Logarithmic scaling. The scaling scheme you select will determine your options for selecting the bar widths. 
  • Linear scaling:  
    • Choose Automatic if you want the program to set the bin width automatically.  For linear plots, the histogram bars will be set to 1/10 the standard deviation.  Example:

    

    • Choose Manual to override the automatic settings, for linearly-scaled plots. Enter this in terms of the variable's actual units, as represented along the x-axis. Example:

    

     

  • Logarithmic Scaling:
    • Choose Automatic if you want the bins to represent equal sampling ranges and to be sized automatically to 1/10^th the standard deviation.  In this example the bins represent equal sampling ranges and will be sized automatically to 1/10^th the standard deviation.  Compare this method (left) versus the Automatic Linear method (second).  Both contain bins of 1/10^th the standard deviation. 

    

    • Choose Manual if you want the bins to represent equal sampling ranges but want to establish the width manually. Enter this in terms of the variable's actual units, as represented along the x-axis. Example:

    
     

  • Confirm Range: Insert a check here to see / override the data range before plotting.  This setting also allows you to define the minimum and maximum values to be displayed on the horizontal axis.  For example, the data range may be 32.455 - 194.89, and you could override this to 0 - 200 for plot consistency.
    ! This can be helpful to create a series of graphs that are scaled the same regardless of the data range.
     
• Bin Colors: Expand this item to select how the histogram bars are to be filled. 
  • Monochrome: Select a color to be used for all bins by clicking on the Color box. 
  • Discrete: Colors are varied, based on statistics.  You can choose a different color for the following bin types:
    • Background: Represents mean + one standard deviation (1SD) and mean - 1SD. These samples show no anomaly.
    • Slightly Anomalous: Represents mean - 1SD to mean - 2SD and mean + 1SD to mean + 2SD. These samples show slight anomaly.
    • Moderately Anomalous: Represents mean - 2SD to mean - 3SD and mean + 2SD to mean + 3SD. These samples show moderate anomaly.
    • Strongly Anomalous: Exceeds mean - 3SD and mean + 3SD. These samples show strong anomaly.
  • Continuous: Choose this to display the bars using a cold-to-hot color scheme (cold for background, hot for anomalous).
    • Maximum Standard Deviation: Use this setting to define the maximum standard deviation which will be used as the boundary for the hot colors.
       
• Plot Statistics: Insert a check here to include labels that represent the groupings of histogram bars into mean + and - 1SD, 2SD, 3SD and 4SD. These would correspond to the anomalous colors above. Expand this item to establish the label color and size (as a percent of diagram width.).
  • Verbose: Leave this check-box blank if you want the statistics labels to include only notations of Mean, Mean + 1SD, Mean - 1SD, Mean + 2SD, Mean - 2SD, etc. Insert a check in this box if you want more wordy statistics labels, to include the above and notations of "Background," "Anomalous," "Slightly Anomalous," "Strongly Anomalous."
     
• Plot X Axis Labels: Insert a check here to plot labels along the bottom axis that represent the real number units of the variable being plotted. Expand this item to establish the label color and size (as percent diagram width).
   
• Plot Y Axis Labels: Insert a check in this box to plot labels along the vertical axis that represent the frequency units. Expand this item to establish the color, size and units. 
  • Plot as Percentages: Insert a check in this check-box if you want the units to represent percent.  If this box is cleared, the units will represent actual occurrences.
     
• Statistical Legend: Insert a check here to include a legend listing a statistical summary for the data.  (The same summary, actually, that is available in the P-Data / Statistics option.)  An example is shown on the right side of the histogram at the top of this topic.
  Expand this heading to access the legend layout options.
  • Dimensions & Position:
    • Width: Set the width for the legend as a percent of the output diagram width. (Default = 30)
    • Height: Set the height for the legend as a percent of the output diagram height. (Default = 100)
    • Horizontal (X) Offset: This setting determines how far, as a percent of the diagram width, the legend is to be offset from the main diagram.  The greater the value you enter, the further the legend will be offset from the diagram.  (Default = 2)
    • Vertical (Y) Offset: Determines how far, as a percent of the diagram height, the legend is to be offset vertically in relation to the diagram. (Default = 0)
  • Plot Border: Check this box to include a line border around the legend; expand this heading to select the line style, thickness, and color.
  • Plot Legend Title: Check this box to display a title label at the top of the legend. Expand this heading to define the title text and font color.
  • Plot Horizontal Dividers: Check this box to plot horizontal lines between each line of text. Expand this heading to select the line style, thickness, and color.
  • Plot Vertical Divider: Check this box to include a vertical divider line between the two columns of text in the legend.  As for the others, expand this item to access the line options.
  • Left Text Column: Expand this heading to define the color and justfication (left, right, centered) of the statistics labels in the left column of the legend.
  • Right Text Column:  Expand this to define the color and justification of the computed statistical values in the right column of the legend.
     
• Fixed Diagram Size:  Check this box if you wish to define a specific size for the graph, helpful should you be creating a series of plots that need to be the same size.  Expand this heading to enter the width and height in diagram units.
  ! Note that the diagram can be enlarged and reduced when displayed on the screen and output to the printer.
  ! The relative aspect (height/width) ratio must be in the same ballpark as the original data range. If the height/width ratio is too large it may result in large gaps in annotation; if too small you may see overplotted annotation.
   

Step-by-Step Summary

1. Access the RockWorks Borehole Manager program tab. 
2. Enter/import your data into the Borehole Manager.
3. Be sure the boreholes whose data you wish to process are enabled.
4. Select the P-Data | Histogram menu option. 
5. Enter the requested menu settings, described above.
6. Click the Process button to continue.

The program will read the selected track of data for the enabled boreholes and apply any requested filtering operations.  If the Confirm Range option was selected, the program will display the data range in a window. 

7. You can override the minimum and/or maximum entries to extend the range of the axis. For example, if the data range as displayed in the window is 21 - 74, then that would be the range of the horizontal axis if left unchanged. If overridden to 0 - 100, then the axis itself would extend from 0 to 100 units. 
8. Click OK to continue. 

The program will then determine the number of remaining samples that fall into each of the histogram "bins," counting them either as actual frequencies or as percent. The completed histogram plot will be displayed in a RockPlot2D tab in the Options window. 

9. You can adjust any of the diagram option in the pane to the left (adjust color scheme, change scaling, etc.) and then click the Process button again to regenerate the histogram.

   ! Each time you click the Process button, the existing display will be replaced. 

10. View / save / manipulate / print / export the diagram in the RockPlot2D window. 
    
    

 Back to P-Data Menu Summary 

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