proc getdata |

Version 2.41 Mar2009
Scripts
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Manual page for proc_getdata(PL)
proc getdata gets data for plotting,
and must be invoked before plotting any data.
Data may be read from files, from commands, or specified directly, and various
input data formats
are supported.
The data which are read become the
current data set
that subsequent plotting procs will access,
and replace any data that were read in (or generated) previously.
proc getdata will set the variable NRECORDS to the number of data rows gotten.
The variable NFIELDS will be set to the number of fields per data row.
Use showdata: yes to check that ploticus is parsing your data as expected.
See also
Discussion of input data formats and parsing rules
Discussion of working with multiple data sets
Attributes
Be sure and set the delim attribute appropriately when using field delimitations other than whitespace-delimited.
Specifying a data source
One (and only one) of the following data sources must be specified:
pathname
filename
-
-
Name of a file containing plotting data.
The file will be opened directly.
Security concern: user-supplied values, such as CGI user variables, should not be used to build the pathname,
unless proper measures are taken to detect and remove the ../ construct (used as a hack
to see higher levels of the file system).
file
filename
-
-
Shell-expandable name of a file containing plotting data.
This name will be used along with cat(1) in a shell command, thus
exported shell variables and metacharacters may be part of the name.
A dash (-) may be used if data is to be read from the standard input,
(or the standardinput attribute may be used).
Security concern: user-supplied values, such as CGI user variables, should not be used to build filename.
On win32 platforms, or when operating in
direct CGI mode
(2.31-08+)
filename automatically maps to pathname .
Example: filename: myfile.dat
data
multiline-text
-
-
Literal specification of plotting data. Terminates at first blank (empty) line.
Best practice is for rows to not have any leading whitespace, and for the first row
of data to be on the line following the data tag, as shown below.
The first row of data may be a field name header.
Use showdata: yes to verify that your data are being input and parsed as expected.
Example:
data:
Case_1 0 4 4.1
Case_2 1 5 4.4
Case_3 2 2 4.0
Case_4 3 9 4.8
command
shell command line
-
-
An external shell command that will produce plot data on its standard output.
Security concern: user-supplied values, such as CGI user variables, should not be used to build the shell command.
If this must be done, use #shell / #endshell along with data:, which provides some protection against
shell metacharacter hacks.
Example: command: cat mydat | uniq -c
commandmr
multi-row shell command
-
-
Same as command but shell command can occupy multiple rows, and is is terminated by a blank line.
Command can be up to ~1000 characters long.
Security concern: user-supplied values, such as CGI user variables, should not be used to build the shell command.
If this must be done, use #shell / #endshell along with data:, which provides some protection against
shell metacharacter hacks.
You can overlay flow-of-control directives as in this example:
commandmr: cat foo.dat |
process_step1 |
#if @sortmode = 1
sort +2 -3
#else
cat -
#endif
standardinput
yes | no
-
-
If yes, data stream is read from the ploticus standard input.
sql
sql command
-
-
Submit the given sql command and capture the results as tabular data,
using sql result column names as the field names.
This is currently available only for builds related to the
QUISP/SHSQL
package.
sqlmr
multi-row sql command
-
-
Same as sql but SQL command can occupy multiple rows, and is is terminated by a blank line.
Command can be up to ~1000 characters long.
You can overlay flow-of-control directives as in this example:
sqlmr: select id, lastname, firstname, balance
from accounts
#if @mode = 1
where acct_type = g
#endif
#intrailer
-
-
Indicates that a data attribute
will be given in a #proc trailer, at the end of the script file.
See EXAMPLES, below.
Characteristics of the data stream
delim
whitespace | spacequote | comma | tab | bar | auto
-
-
Field delimitation used in the data set.
Default is spacequoted.
Use auto to have ploticus attempt to automatically determine the delimitation (2.40+). See
dataformat
for details.
Example: delim: comma
nfields
n
-
-
If specified, this sets the expected number of fields per record.
If a data row has more than the expected number of fields, extra fields are silently ignored.
If a data row has less than the expected number of fields, blank fields are silently added.
This is applied after any filter processing.
If not specified, the first non-comment non-header row encountered will set the expected number of fields.
commentchar
string
-
-
A character or group of characters that is used to signify a comment in the data file.
Commented lines will be skipped. Default is //.
Example: commentchar: #
Setting field names
fieldnameheader
yes | no
-
-
Allows field names to be embedded in the input data.
If yes, the first non-comment line in the data is expected to
contain field names. This line is not considered part of the data.
The field name header should be delimited like the rest of the data.
Field names may not contain embedded white space, commas, or quote characters
but (2.30+) there is a way to encode spaces and commas... see
proc settings encodenames.
fieldnames
namelist
-
-
Specify field names for input data fields.
namelist is a list delimited by spaces and/or commas.
Names may include any alphanumeric characters with a maximum length of 48, and are case-insensitive.
Field names may not contain embedded spaces or commas,
but (2.30+) you can encode them... see
proc settings encodenames.
Note: if you are using a filter (see below) you may want to use pf_fieldnames
(see below) to name the result fields.
Example: fieldnames: date group n
fieldnamerows
multiline text
-
-
Same as fieldnames (see above), except that field names are given one per line.
Must be terminated by a blank line.
Example:
fieldnamerows:
id
type
age
sex
pf_fieldnames
namelist
-
-
Assign new field names to filter result.
See filter attribute described below.
Useful when the filter result has a different logical record format than the input.
See also fieldnames above.
Example: pf_fieldnames: date z sum1 sum2
Development & debugging
showdata
yes | no
(old name showresults)
-
-
If yes, the data as read, parsed, and filtered are written to the diagnostic file in bar-delimited format.
Selecting and manipulating input rows
select
select expression
-
-
This allows certain data records to be selected for inclusion based
upon a
selection expression.
Incoming data fields are referenced by number,
using a double at-sign (@@) prefix.
Hint: use the showresults attribute when debugging.
Example: select: @@3 = g
This would select all data records having 3rd field equal to g.
rotate
yes | no
-
-
This attribute discontinued as of 2.40</b>... use
proc processdata, action: rotate
instead.
filter
multiline text
-
-
An embedded script which allows flexible processing to be applied to
incoming data records one at a time.
Typical uses are for
concatenating or splitting fields, doing on-the-fly date conversions,
or generating derived fields such as the sum of several fields or the difference
between two fields.
-
-
The embedded script will be applied once to every incoming data record.
The script should produce some "output"; generally the last statement is a
##print.
The output must use the same delimitation method as the input.
The output may have a different logical record format than the input.
If you are using field names,
the pf_fieldnames attribute (see above) may be used to name the
filter result fields when result record format differs from that of the input.
-
-
The script uses the same syntax as the greater ploticus script, except that:
-
-
directives must begin with two pound signs (##) instead of one
-
local variables begin with two at signs (@@) instead of one
-
fields on the incoming data record are accessed like this: @@1 for
the first field, @@2 for the second, etc. If you are using field
names, these may be used as well, eg: @@score.
-
the only directives that may be used are
##set, ##if, ##elseif, ##else, ##print, ##call,
and ##exit
-
-
Other things worth noting:
-
More examples
Data specification may be located at the end of the script file
by using #intrailer and #proc trailer. This may be
useful in "getting the data out of the way", or with automated building
of script files.
Here is how this is done:
#proc getdata
#intrailer
other #procs, etc.
#proc trailer
Data: 0.3 0.5 2.3
3.5 9.4 1.4
..etc..
end of file
Variables that are set by proc getdata
NRECORDS = the number of data rows gotten
NFIELDS = the number of fields per record
Hints
The processed, filtered data set result can be written to a tab-delimited file by doing something like this:
-
-
#proc getdata
...
#endproc
#proc processdata
action: echo
outfile: /tmp/myfile
It is possible to
set working variables from within the data file.
During debugging, set showresults: yes in order to see the data after it is read and parsed.
Especially useful when working with filter.
In dynamic content environments it's good to gracefully handle the
situation of an empty data file or command that produced no output. Example:
-
-
#proc getdata
...
#proc endproc
#if @NRECORDS = 0
#proc annotate
location: 3 3
text: No data found.
#exit
#endif
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 data display engine
Copyright Steve Grubb
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