About variables

Echoview uses variables to store, manipulate and display data from an echosounder, a file or another variable. Each variable contains time series measurements from a single data type.

There are Raw, virtual and editable variables which can also be distinguished by their Variable class.

Raw, virtual and editable variables
Variable class
Interacting with variables

Creating and deleting

Raw variables

Raw variable names

Virtual or editable variables

Virtual variable and editable variable names

Editing
Naming

Reserved characters
File name illegal characters

Displaying
Time and Date

See also

Raw, virtual and editable variables

Raw	Echoview derives these from your input data files (such as from the echosounder¹). It does not modify the data file. Raw variables are typically at the root of your workflow.
Virtual	Echoview derives these from operators.
Editable	These are Editable lines and Bottom points variables. You can modify the data samples in editable variables (refer to Editing below).
¹For example, a data file from an echosounder may contain the transmitted and received properties of pings, and the geographic location of a ship at the ping broadcast time. From this, Echoview would derive one or more raw variables, such as an Sv variable, TS variable and a position variable.

Variables are divided into the following classes:

Acoustic	Measurements from the transmitted and received properties of a ping. The data type of an acoustic variable may not be the same as the type of data stored in a data file².
Geopoint	Measurements with associated time, latitude, longitude and altitude. Echoview only supports bottom points variables of this class.
Image	Contains image data.
Video	Contains video data.
Position	GPS fix measurements.
Time series	A time series consists of measurements and their measurement times. Time series may be derived from data files or output by Echoview operators.
Time series collection	A set of time series. A time series collection may be derived from data files or output by Echoview operators, and can be exported as a single table for reuse in Echoview or external analysis.
²For example, a data file may contain voltage measurements from an echosounder. Echoview might derive an acoustic data type Sv variable from these measurements.

Interacting with variables

Echoview variables exist in EV files.

Use the Dataflow window to interact with the different kinds of variables, or use the Filesets window to investigate raw variables. Right-click on a variable to open the shortcut menu and list the available options.

You can also interact with variables via the Echoview command interface or with COM scripts (refer to About automating Echoview).

Creating and deleting

Raw variables

Echoview creates raw variables when you load data into an EV file.

You cannot delete Echoview raw variables.

Raw variable names

Echoview automatically derives the raw variable names, depending on the source of the data.

Refer to these pages for the syntax Echoview uses in each case.

Virtual or editable variables

Refer to Creating and deleting virtual variables.

Virtual variable and editable variable names

When you create a new virtual or editable variable, Echoview automatically gives it a name appended with an index.

Starting from index 1, Echoview increases this index for new variables with the same name. The algorithm does not skip numbers in the index sequence.

Editing

You can only modify the data samples in Editable lines and Bottom points variables.

Refer to Creating, editing, renaming and deleting lines and Bottom classification analysis options.

Naming

Each variable must have a unique name. Echoview provides International character support for variable names.

To rename a variable, select it in the Dataflow window. Then click on its name or press F2. A reset to default name feature is available under a variable's or object's Name and Notes page of the Variable Properties dialog box. A Dynamic name feature may be available to some variables and objects.

Names are case-insensitive, and whitespace-insensitive. See also: General variable name-uniqueness notes and command interface reserved keywords.

Reserved characters

Names cannot contain these reserved characters or words:

[tab]
"
*
,
|
AUX
COM[0...9]
CON
default
LPT[0...9]
PRN
none
NUL

File name illegal characters

Variable names cannot be a combination of these file name illegal characters:

: ? < > \ /

Displaying

To inspect the data of that variable—depending on the variable class—you can open its:

Time and date

Variable operators may have settings to specify the time and date for a range of pings. Echoview uses an abbreviated ISO 8601 format where valid times and dates lie between 1970 and 2050. See Ping subset: Time (valid ranges from 1970 to 2050) for information on formatting.