CSV — Tables and Matrices

ccalc provides three built-in functions for reading and writing delimiter-separated files. They extend the lower-level dlmread/dlmwrite primitives with automatic header handling, mixed-type columns, and RFC 4180 quoting.

readmatrix

readmatrix(path) reads a numeric CSV file and returns a Matrix.

A = readmatrix('data.csv')

Behaviour:

• Auto-detects the delimiter: comma → tab → whitespace.
• If the first row contains any non-numeric text it is skipped as a header. A purely numeric first row is treated as data.
• Empty cells become NaN (unlike dlmread, which uses 0.0).

% data.csv:  x,y,z\n1,2,3\n4,5,6
A = readmatrix('data.csv')
% → [1 2 3; 4 5 6]  (header row skipped)

Explicit delimiter:

A = readmatrix('data.tsv', 'Delimiter', '\t')

readtable

readtable(path) reads a CSV file where the first row is always the header and returns a Struct of columns.

T = readtable('people.csv')
T.name    % Cell of Str — one element per row
T.age     % Matrix (N×1) — numeric column

Column type rules:

Quoted fields (RFC 4180):

Fields may be enclosed in double-quotes. A comma inside a quoted field is part of the value, not a delimiter. Two consecutive "" inside a quoted field encode a literal ".

% people.csv:
%   name,city
%   "Smith, John","New York"
T = readtable('people.csv')
T.name{1}   % → 'Smith, John'
T.city{1}   % → 'New York'

Explicit delimiter:

T = readtable('data.tsv', 'Delimiter', '\t')

writetable

writetable(T, path) writes a struct table to a CSV file with a header row.

T.name  = {'Alice'; 'Bob'};
T.score = [95; 87];
writetable(T, 'output.csv')

Output:

name,score
Alice,95
Bob,87

Accepted column types:

Quoting: any cell value that contains the delimiter, a ", or a newline is automatically wrapped in double-quotes (RFC 4180). Embedded " are doubled.

T.desc = {'hello, world'; 'plain'};
T.n    = [1; 2];
writetable(T, 'out.csv')
% out.csv:
%   desc,n
%   "hello, world",1
%   plain,2

Explicit delimiter:

writetable(T, 'out.tsv', 'Delimiter', '\t')

Roundtrip example

% Write
T.city  = {'Paris'; 'Berlin'; 'Tokyo'};
T.pop   = [2161000; 3645000; 13960000];
writetable(T, 'cities.csv')

% Read back
T2 = readtable('cities.csv')
T2.city{2}   % → 'Berlin'
T2.pop(3)    % → 13960000

Differences from dlmread / dlmwrite