Difference between revisions of "Geopsy: Set header"

From GeopsyWiki
Jump to navigation Jump to search
Line 15: Line 15:
 
  signals[i]
 
  signals[i]
  
−
Refers to the (i+1)th signal in the current viewer. In a table, index are displayed on the left side starting at 1. Be careful that they start at 0 in array ''signals''. The number of signals in the current viewer is return by the expression
+
Refers to the (i+1)th signal in the current viewer. In a table, index are displayed on the left side starting at 1. Be careful that they start at 0 in array ''signals''. The number of signals in the current viewer is given by expression
  
 
  signals.length
 
  signals.length
Line 25: Line 25:
 
  }
 
  }
  
−
In this example, ''deltaT'', the sampling period is set to 0.01 seconds or a sampling frequency of 100 Hz.
+
In this example, ''deltaT'', the sampling period is set to 0.01 seconds or a sampling frequency of 100 Hz. ''print'' function might be useful to solve errors in scripts. Print output and errors are all directed to the main log message window.
  
 +
for(i=0; i<signals.length; i++) {
 +
  print("Signal index "+i+" had a sampling period of "+signals[i].deltaT);
 +
}
  
−
<br style="clear: both"/>
+
Which results into the following message in the log window:
−
 
 
−
Below this point, the information is not related to the latest development release.
 
−
 
 
−
There are various assignment operators working for numbers and character strings:
 
−
SignalData =  value      // Set ''SignalData'' to ''value''
 
−
value1 + value2          // Sum or concatenation operator
 
−
SignalData += value      // Set ''SignalData'' to the sum of its previous content with ''value''
 
−
value1 == value2  // Returns a bool value, true if ''value1'' and ''value2'' are equal
 
−
value1 != value2  // Returns a bool value, true if ''value1'' and ''value2'' are not equal
 
−
 
 
−
Some assignment operators work only for numbers:
 
−
value1 - value2          // Difference operator
 
−
value1 - value2          // Multiplication operator
 
−
value1 / value2          // Floating point division operator
 
−
value1 DIV value2        // Integer division operator. E.g. 5 DIV 2 produces 2
 
−
value1 < value2  // Returns a bool value, true if ''value1'' is less than ''value2''
 
−
value1 ≤ value2  // Returns a bool value, true if ''value1'' is less than or equal to ''value2''
 
−
value1 > value2  // Returns a bool value, true if ''value1'' is greater than ''value2''
 
−
value1 ≥ value2  // Returns a bool value, true if ''value1'' is greater than or equal to ''value2''
 
−
SignalData -= value      // Set ''SignalData'' to the difference between its previous content and ''value''
 
−
SignalData *= value      // Set ''SignalData'' to the product of its previous content with ''value''
 
−
SignalData /= value      // Set ''SignalData'' to the ratio between its previous content and ''value''
 
−
                            A floating point division is performed
 
−
value1 [ value2 ]  // If ''value1'' is an array, the ''value2'' th  element is returned.
 
−
                            If ''value1'' is not an array, ''value2'' is ignored.
 
−
 
 
−
 
 
−
Additionally, you have access to some useful functions for text manipulation or for conditional operations:
 
−
if(value1, value2, value3)        // If ''value1'' evaluates to true, ''value2'' is returned else ''value3''
 
−
justify(string, nchar, fillchar)  // Right justifies ''string'' to get a ''nchar'' length. Blanks are filled with ''fillchar''. 
 
−
                                      ''fillchar'' must be 1 character length. E.g. justify( "45", 5, "0") produces "00045".
 
−
left(string, nchar)              // Returns the first ''nChar'' characters of ''string''. E.g. left("45678",2) returns "45"
 
−
length(string)                    // Returns length of ''string''. E.g. length("45678") returns 5
 
−
mid(string, pos, nchar)          // Returns ''nChars'' characters of ''string'' starting at ''pos''. ''pos'' starts counting at 0.
 
−
                                      E.g. mid("45678", 1, 2) returns "56".
 
−
right(string, nchar)              // Returns the last ''nChar'' characters of ''string''. E.g. left("45678",2) returns "78"
 
−
 
 
−
 
 
−
Any unrecognized name not starting by a number is considered as a custom variable. Custom variables are initialized by an empty string if there not in the left part of "=" assignment. They can be used in formulas like any constant or signal data.
 
−
 
 
−
When you click on [[Image:ApplyButton.png|middle]], all equations are executed for all signals in the order the equations appear in the editor and in the order of signals in the viewer. Custom variables are persistent during the global loop. This way values can be "propagated" from the first signals to the next one.
 
−
 
 
−
The content of the editor can be saved or restored to a .headequ file (a simple text file in fact) by clicking on the button [[Image:SaveButton.png|middle]] and [[Image:LoadButton.png|middle]] respectively.
 
  
 +
[SetHeader]Signal index 0 had a sampling period of 0.004
 +
[SetHeader]Signal index 1 had a sampling period of 0.004
  
−
<br style="clear: both"/>
+
To execute the current script click on '''Apply'''. The content of the editor can be saved or restored to a .headequ file (a simple text file in fact) by clicking on the button '''Save''' and '''Load''' respectively.
  
 
== Examples ==
 
== Examples ==

Revision as of 08:53, 12 August 2011

This section explains how to modify header information stored in a database in a very efficient way. Any information about signals can be viewed in a table. Signals can be modified one by one by cell editing (Ctrl+K). For huge number of signals this is boring and time consuming. Instead, you can create small scripts and apply them with one single click. The syntax for these scripts is rather simple. They are based on the ECMAScript scripting language like waveform script language.

General presentation

This help refers to the latest development release (geopsypack>=2.5.0)

Dialog box to editing header information

From any active signal viewer (which is by definition a list of signals), click on menu item Edit/Set headers. A dialog box will appear. You can type any script in the left editor. A basic loop to assign a new name to all signals is proposed as the default script. Comment or remove this script and enter your own code.

All statements are separated by ; (like in C or C++). If a line begins with //, all text is ignored until the end of the line (like C or C++ comments). In the same way, all text included between /* and */ is considered as a comment. Commenting parts of a script may be interesting to solve errors.

Upon starting the script, an array called signals contains the list of all signals of the current viewer. Each signal is indexed by its position in the current viewer, starting at index 0. For instance, 

signals[i]

Refers to the (i+1)th signal in the current viewer. In a table, index are displayed on the left side starting at 1. Be careful that they start at 0 in array signals. The number of signals in the current viewer is given by expression 

signals.length

Hence, the basic loop to assign values to signal headers will have a structure similar to this one: 

for(i=0; i<signals.length; i++) {
  signals[i].deltaT=0.01;
}

In this example, deltaT, the sampling period is set to 0.01 seconds or a sampling frequency of 100 Hz. print function might be useful to solve errors in scripts. Print output and errors are all directed to the main log message window. 

for(i=0; i<signals.length; i++) {
  print("Signal index "+i+" had a sampling period of "+signals[i].deltaT);
}

Which results into the following message in the log window: 

[SetHeader]Signal index 0 had a sampling period of 0.004
[SetHeader]Signal index 1 had a sampling period of 0.004

To execute the current script click on Apply. The content of the editor can be saved or restored to a .headequ file (a simple text file in fact) by clicking on the button Save and Load respectively.

Examples

Example 1 : Modify signal names

ShortFileName is the original file name without its complete path. The name of the signal is extracted from the ShortFileName. 

Name=mid( ShortFileName,3,5 );

Example 2 : Set the sampling frequency to 100 Hz

Set sampling frequency to 100 Hz. Can be useful when loading signal from text files without header information. The sampling frequency is the minimum field required to display signals. 

SampFreq=100;

Example 3 : Set the components

Set the component from the signal file name. ShortFileName is the original file name without its complete path. We assume that the file name contains a keyword indicating the component. 

if(mid( ShortFileName, 12, 1 )=="E", Component="East");
if(mid( ShortFileName, 12, 1 )=="N", Component="North");
if(mid( ShortFileName, 12, 1 )=="Z", Component="Vertical");

Example 4 : Set comments

The comments contains here the name of the array. 

 Comments="RING01"

The application of the equations shown is the examples No 1, 2, 3 and 4 modify the headers as follow:

Modified headers after applying the equations shown in examples 1 to 4
Retrieved from "https://www.geopsy.org/wiki/index.php?title=Geopsy:_Set_header&oldid=3177"