csv(n) 0.4 csv "CSV processing"
csv - Procedures to handle CSV data.
package require Tcl 8.3
package require csv ?0.4?
The csv package provides commands to manipulate information
in CSV FORMAT (CSV = Comma Separated Values).
The following commands are available:
- ::csv::join values {sepChar ,}
-
Takes a list of values and returns a string in CSV format containing
these values. The separator character can be defined by the caller,
but this is optional. The default is ",".
- ::csv::joinlist values {sepChar ,}
-
Takes a list of lists of values and returns a string in CSV format
containing these values. The separator character can be defined by the
caller, but this is optional. The default is ",". Each element of the
outer list is considered a record, these are separated by newlines in
the result. The elements of each record are formatted as usual (via
::csv::join).
- ::csv::read2matrix ?-alternate? chan m {sepChar ,} {expand none}
-
A wrapper around ::csv::split2matrix (see below) reading
CSV-formatted lines from the specified channel (until EOF) and adding
them to the given matrix. For an explanation of the expand
argument see ::csv::split2matrix.
- ::csv::read2queue ?-alternate? chan q {sepChar ,}
-
A wrapper around ::csv::split2queue (see below) reading
CSV-formatted lines from the specified channel (until EOF) and adding
them to the given queue.
- ::csv::report cmd matrix ?chan?
-
A report command which can be used by the matrix methods
format 2string and format 2chan. For the latter this
command delegates the work to ::csv::writematrix. cmd is
expected to be either printmatrix or
printmatrix2channel. The channel argument, chan, has
to be present for the latter and must not be present for the first.
- ::csv::split ?-alternate? line {sepChar ,}
-
converts a line in CSV format into a list of the values
contained in the line. The character used to separate the values from
each other can be defined by the caller, via sepChar, but this
is optional. The default is ",".
If the option -alternate is spcified a slightly different
syntax is used to parse the input. This syntax is explained below, in
the section FORMAT.
- ::csv::split2matrix ?-alternate? m line {sepChar ,} {expand none}
-
The same as ::csv::split, but appends the resulting list as a
new row to the matrix m, using the method add row. The
expansion mode specified via expand determines how the command
handles a matrix with less columns than contained in line. The
allowed modes are:
- none
-
This is the default mode. In this mode it is the responsibility of the
caller to ensure that the matrix has enough columns to contain the
full line. If there are not enough columns the list of values is
silently truncated at the end to fit.
- empty
-
In this mode the command expands an empty matrix to hold all columns
of the specified line, but goes no further. The overall effect is that
the first of a series of lines determines the number of columns in the
matrix and all following lines are truncated to that size, as if mode
none was set.
- auto
-
In this mode the command expands the matrix as needed to hold all
columns contained in line. The overall effect is that after
adding a series of lines the matrix will have enough columns to hold
all columns of the longest line encountered so far.
- ::csv::split2queue ?-alternate? q line {sepChar ,}
-
The same as ::csv::split, but appending the resulting list as a
single item to the queue q, using the method put.
- ::csv::writematrix m chan {sepChar ,}
-
A wrapper around ::csv::join taking all rows in the matrix
m and writing them CSV formatted into the channel chan.
- ::csv::writequeue q chan {sepChar ,}
-
A wrapper around ::csv::join taking all items in the queue
q (assumes that they are lists) and writing them CSV formatted
into the channel chan.
The format of regular CSV files is specified as
-
Each record of a csv file (comma-separated values, as exported e.g. by
Excel) is a set of ASCII values separated by ",". For other languages
it may be ";" however, although this is not important for this case as
the functions provided here allow any separator character.
-
If and only if a value contains itself the separator ",", then it (the
value) has to be put between "". If the value does not contain the
separator character then quoting is optional.
-
If a value contains the character ", that character is represented by "".
-
The output string "" represents the value ". In other words, it is
assumed that it was created through rule 3, and only this rule,
i.e. that the value was not quoted.
An alternate format definition mainly used by MS products specifies
that the output string "" is an representatation of the empty
string. In other words, it is assumed that the output was generated
out of the empty string by quoting it (i.e. rule 2), and not through
rule 3. This is the only difference between the regular and the
alternate format.
The alternate format is activated through specification of the option
-alternate to the various split commands.
Using the regular format the record
| |
123,"123,521.2","Mary says ""Hello, I am Mary"""
|
is parsed into the items
| |
a) 123
b) 123,521.2
c) Mary says "Hello, I am Mary"
|
matrix, queue
csv, matrix, package, queue, tcllib
Copyright © 2002 Andreas Kupries <andreas_kupries@users.sourceforge.net>