DB_HISTO

COMMAND TYPE : GRAPHIC

PURPOSE:

By this command you can display on a graphic terminal an histogram or a pie-chart of the field values present in one (or more) catalogue.

DESCRIPTION:

The command draws an histogram or a pie-chart of a numerical, or character field, present in one or more catalogues. Many histogram types are available in this task and they can be selected with 'FORmat' key.

When the user works on numerical value he can select continuum or discrete histogram type using 'HIStogram' verb. The user must use a discrete histogram when the numerical values are used as a 'code'. Working on characters fields only discrete histogram is allowed.

Working with many catalogues the user can superimpose or add-up the values of different catalogues using the 'SUMmarize' flag. When an 'ALL' command is executed the histograms will have the desired aspect. Drawing an histogram at a time with the 'DISplay' command the 'SUMmarize' flag has no effect. The 'YMAx' and 'YMIn' values define the scale of the histogram. When these values are not set the scale is defined by the values of the first histogram drawn. Then when the user needs to draw many histograms, in the same picture, he must draw the highest histogram first.

On a continuum histogram the user can compute statistical parameters and superimpose a gaussian curve with the 'MEAn' and 'GAUssian' verbs. The comparison of two or more histograms can be simple by using the 'NORmalize' flag.

REQUIRED Parameters Verb

These parameter verbs are required for the execution of the task.

CATalogue Opens Catalogue
VARiable Catalogue Variable
MAXimum Max value on a numerical 'VAR'

SPECIFIC VERBS

The task uses all the command verbs defined in section , moreover specific verbs are :

ALL Execution

Executes the main operations of the task on all catalogues currently opened. When you have opened more than one catalogue you get different results using several 'DISplay' command verbs or the 'ALL' verb. This verb verifies if a 'SUMmarize' flag is set, to get a piled histogram. When you are working with discrete type variables in more catalogues and the 'SUM' parameter is set to 0, you get near-flank bars.

BINs Data
Number of bins of a continuum type histogram. Default is 16, maximum is 255. Using discrete histogram this verb has no effect.

Example: HIS> BIN 30

FILl Data Parameter

Defines how to fill the histogram bars. When this value is set to 0 the bars are unfilled. The pattern used to fill the bars is device dependent. You can show the pattern codes using the command 'LUT'.

FORmat Data Parameter
Define the type of graphic objects that are displayed

Valid Forms: 
0  -   Bars (defaults)
1  -   Lines
2  -   Lines and symbols
3  -   Pie-chart

Example: HIS> FOR 2

GAUssian Execution
Draws a gaussian curve superimposed to an histogram with appropriate mean and root mean square and write the fit parameters on the screen and into the log file. Before using the 'GAUssian' verb you must use the 'AVErage' command to calculate the arithmetic mean and the r.m.s. of the histogram. This command doesn't work when you have many catalogues displayed on the screen.

HIStogram Grid

Defines the type of the histogram when you are working on a numerical 'VARiable'. When this flag is set to 0 you get a continuum histogram, when this flag is set to 1 you get a discrete histogram. Working on character strings you can have discrete histogram only. Default is 0.

Example: HIS> HIS 1

LISt Execute
Writes in a file the values of the histogram bins for all the catalogues opened. Before to use this command it is useful to enter a 'ALL' command to reset the histogram values of all the open catalogue.

LIMits Variable Parameter
Discrete histogram only. With this verb you can define the range of the numerical value of the catalogue variable related with a bin. 'SAMple' defines the type of relation that you can have between data and bins. The number of parameters following the verb defines the number of bins: (max 8), if there are N value only the 'LIMits' from 1 to N are updated.

Example: HIS> LIM 1.5 2. 3. 5.5 7. 12. 20.

NORmalized Grid and Display

When this flag is set to 1 you get a normalized histogram: The maximum on the Y axis is set to 100 and the highest bin is set to this value. You can not use this flag when 'YMAx', 'YMIn','YLOg' are set. Default is 0

Example: HIS> NORm 1

PATtern Variable Parameter

With this verb you can define the comparison strings that define the bins. 'SAMple' defines the type of relation that you are going to use. The number of parameters following the verbs defines the number of bins (Max 8). If there are N values only the 'PATterns' from 1 to N are defined. The key OTHER collects in this bin all the other objects of the catalogue.

Example: HIS>PAT Sa Sb Sc S0 DWARF E OTHER

SAMple Variable
Defines how the 'LIMits'/'PATtern' are used in the selections. On numerical value 'SAMple' can be 0-1-2. The catalogue value will be displayed with N-th symbol if:

On character string 'SAMple' can be 0-1. The catalogue string will be displayed with N-th symbol if:

0  PATtern(N)  = string
1  PATtern(N)  match string

SIZe Variable
Defines a size in the numerical selection: see 'SAMple' verb for more details.

SUMmarize Data
When many catalogues are opened and this flag is set to 1 you can display data as a piled histogram. You must use the 'ALL' command. Default is 0.

Example: HIS> SUM 1

VARiable Variable Parameter
Defines the catalogue field that you will use in the histogram. If 'VARiable' refers to a numerical value you must define 'MAXimum' and 'LIMits' (if you work on a discrete histogram) otherwise you must define 'PATtern'. If you answer ' ? ' at the prompt, you get a list of available variables on the catalogue. The VARiable can be a single catalogue field or a function of catalogue fields.

Example: HIS> VARiable MAG

YLOg Grid
If this flag is set you define a logarithmic scale on the Y axis. Default value is 0.

Example: HIS> YLog 1

YMAx Variable
Defines the maximum value for the Y axis. If this value is not set the maximum of this scale is automatically defined by the highest bin.

Example: HIS> YMAx 120

YMIn Grid and Display
Defines the minimum value for the Y axis. Default is 0.

Example: HIS> YMIN 10

DB_HISTO Summary of the commands

* = must be provided by the user

Command Explanation Ref.

---- Execution

ALL Executes GRI and DIS on all cat. Verb AUToscale Calculates max and min Verb AVErage Evaluates the average of VAR Verb DISplay Displays Data Verb EXIt Exits from task Verb GAUssian Draws a computed gaussian curve Spec GO Executes the task Verb GRId Draws the grid Verb LISt Writes a data file Spec SYStem Returns to VMS Verb TEXt Draws a string of text Verb

---- Set up and selection

ACTive Defines active catalogue Verb * CATalogue Opens a Catalogue Verb CLOse Closes a catalogue Verb CONstrains Sets constraints on active cat. Verb CVAriable Defines cord. variables name Verb DEC Sets Dec. coordinates limits Verb DWIndow Resets window condition Verb DZOom Resets zoom condition Verb LATitude Sets longitude cord. Verb LONgitude Sets latitude cord. Verb RA Sets R.A. coordinate limits Verb SELect Fields listed in LISt Verb WDEc Sets a window in Dec. Verb WLAtitude Sets a window on LAT. Verb WLOngitude Sets a window on LON. Verb WRA Sets a window in R.A. Verb

---- Variables

LIMits Range of VAR Spec * MAXimum Maximum value of VAR Verb MINimum Minimum value of VAR Verb PATterns Strings used in the selection Spec SAMple Type of selection Spec SIZe Size of numerical selection Spec * VARiable Variable used Spec YMAximum Maximum value on Y axis Spec YMInimum Minimum value on Y axis Spec

---- Grid

DGRid Resets default grid values Verb FONt Font type Verb GCOlor Color of the grid Verb HIStog Continuum or discrete histogram Spec LSIze Sets the label size Verb VFOrmat FORTRAN format of labels in X Verb XSTep Sets the number of steps in X Verb YLOg Log. scale in Y Spec YSTep Sets the number of step in Y Verb YVFOrmat FORTRAN format of labels in X Verb

---- Data

BINs Number of bins Spec COLors Color of the mark Verb FILl Fill histogram bars Spec FORmat Type of histogram Spec MSIze Sets the size of the marks Verb NORmalized Values normalized in the histog. Spec SUMmarize Piled histogram Spec SYMbol Sets the marks type Verb

---- Screen

CLEar Clears graphic device Verb CLS Clears command monitor Verb MONitor Number of rows in command monit. Verb NOWindow Don't draw window box Verb W2 Redraws graphic windows Verb

---- Help

? List of the commands Verb HELp Help of a command Verb LFOnt Shows available font Verb LUT Shows available colors Verb SHO Shows a parameter value Verb

---- Hard copy

HARd Executes an hard copy Verb HDEvice Defines hard copy device Verb HDImension Defines hard copy dimensions Verb

---- Log file

BREak Sets a break flag Verb DElete Deletes a log file Verb LOAd Loads an existent log file Verb NEXt Continues the load after a BREak Verb REM Writes a string in the log file Verb SAVe Saves current log file Verb

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