LET STRING

LET STRING

Analysis Command

Defines a string.

In addition to parameters and vectors of real numbers, DATAPLOT allows you to define strings. Strings can be created using either the READ STRING or the LET STRING commands.

Strings are often used with the substitution character ("^" by default). The substitution character inserts the value of a previously defined parameter or string into a DATAPLOT command. For example,

LET STRING S = Glucose in Serum
TITLE ^S


Although in this example we could have simply entered the string directly in the title, this capability can be useful in writing general purpose macros and within loops.

LET STRING <sout> = <sin>
where <sout> is the name of the string;
and <sin> is an expression that defines the contents of the string.

LET STRING S1 = Sample String

Internally, Dataplot stores functions and strings together. However, there is one important distinction between LET STRING and LET FUNCTION. The LET STRING comamnd will preserve the case of the text used to define the string while LET FUNCTION will automatically convert lower case characters to upper case.

Dataplot does not currently support string arrays. You can mimic this capability to some extent using the substitution character ("^" by default). For example, you could do somehting like

 
let string s1 = Title for Plot One
let string s2 = Title for Plot Two
let string s3 = Title for Plot Three
loop for k = 1 1 3
     title ^s^k
     plot y^k x
end of loop
    

The total number of characters that DATAPLOT can use for storing functions and strings is set when DATAPLOT is built. The current default (11/2008) is 50,000 characters. Previous versions may set this limit at 1,000 or 10,000 characters. This limit applies to the combined number of characters for all functions and strings.

None

None

UPPER CASE	= Convert a string to upper case.
LOWER CASE	= Convert a string to lower case.
LET FUNCTION	= Defines a function.
READ STRING	= Reads a string from a file.
SUBSTITUTE CHARACTER (^)	= Substitute the value of a string or parameter.
CONCATENATE CHARACTER (&)	= Concatenate two strings.
SUBTRING	= Extract a substring from an existing string.
STRING INDEX	= Extract the start/stop positions of a substring within a string.
STRING CONCATENATE	= Concatenate one or more previously defined strings.
STRING EDIT	= Edit a string.
STRING MERGE	= Insert a string into another string without overwrite.
STRING REPLACE	= Insert a string into another string with overwrite.
STRING LENGTH	= Return the length of a string.
CHARACTER	= Convert numeric values to strings based on the ASCII collating sequence.
ICHAR	= Convert a string to numeric values based on the ASCII collating sequence.
GROUP LABEL	= Define the text for group labels.

Data Management

Pre-1987

 
.  Assume we have variables X and Y in the files "file1.dat" to
.  "file10.dat" and we want to plot each of these in turn.
.
LET STRING S1 = file
LET STRING S3 = .dat
TITLE CASE ASIS
LOOP FOR K = 1 1 10
    LET STRING S2 = ^K
    LET STRING FNAME = ^S1&^S2&^S3
    READ ^FNAME  Y X
    TITLE Data from File ^SOUT
    PLOT Y X
    DELETE Y X
END OF LOOP