# Array I/O to text files
#
# Written by Konrad Hinsen <hinsen@cnrs-orleans.fr>
# last revision: 2006-6-23
#

"""
Basic support for I/O of one- and two-dimensional numerical arrays to and from plain text files

The text file format is very simple and used by many other programs as
well:

  - each line corresponds to one row of the array

  - the numbers within a line are separated by white space

  - lines starting with # are ignored (comment lines)

An array containing only one line or one column is returned as a
one-dimensional array on reading. One-dimensional arrays are written
as one item per line.

Numbers in files to be read must conform to Python/C syntax.  For
reading files containing Fortran-style double-precision numbers
(exponent prefixed by D), use the module L{extern.scientific_python.IO.FortranFormat}.
"""

from extern.scientific_python.IO.TextFile import TextFile
from extern.scientific_python import N; Numeric = N
import string

def readArray(filename):
    """
    Read array data from a file
    
    This function works for arbitrary data types (every array element can be
    given by an arbitrary Python expression), but at the price of being
    slow. For large arrays, use L{readFloatArray} or L{readIntegerArray}
    if possible.

    @param filename: the name of the file to read
    @type filename: C{str}

    @returns: an array containing the data from the file
    @rtype: C{Numeric.array}
    """
    data = []
    for line in TextFile(filename):
        if len(line) == 0 and len(data) > 0:
            break
        if line[0] != '#':
            data.append(map(eval, line.split()))
    a = Numeric.array(data)
    if a.shape[0] == 1 or a.shape[1] == 1:
        a = Numeric.ravel(a)
    return a

def readFloatArray(filename):
    """
    Read array data from a file into an array of floats
    
    @param filename: the name of the file to read
    @type filename: C{str}

    @returns: an array containing the data from the file
    @rtype: C{Numeric.array} of C{float}
    """
    data = []
    for line in TextFile(filename):
        if line[0] != '#':
            data.append(map(float, line.split()))
    a = Numeric.array(data)
    if a.shape[0] == 1 or a.shape[1] == 1:
        a = Numeric.ravel(a)
    return a

def readIntegerArray(filename):
    """
    Read array data from a file into an array of integers
    
    @param filename: the name of the file to read
    @type filename: C{str}

    @returns: an array containing the data from the file
    @rtype: C{Numeric.array} of C{int}
    """
    data = []
    for line in TextFile(filename):
        if line[0] != '#':
            data.append(map(string.atoi, line.split()))
    a = Numeric.array(data)
    if a.shape[0] == 1 or a.shape[1] == 1:
        a = Numeric.ravel(a)
    return a

def writeArray(array, filename, mode='w'):
    """
    Write a text representation of an array to a file.

    @param array: the array to be written
    @type array: C{Numeric.array}
    @param filename: the name of the output file
    @type filename: C{str}
    @param mode: the file access mode, 'w' (new file) or 'a' (append)
    @type mode: C{str}
    """
    file = TextFile(filename, mode)
    if len(array.shape) == 1:
        array = array[:, Numeric.NewAxis]
    for line in array:
        for element in line:
            file.write(`element` + ' ')
        file.write('\n')
    file.close()

#
# Write several data sets (one point per line) to a text file,
# with a separator line between data sets. This is sufficient
# to make input files for most plotting programs.
#
def writeDataSets(datasets, filename, separator = ''):
    """
    Write multiple datasets to a text file.

    @param datasets: a sequence of datasets describing a curve to be
                     plotted. Each dataset is either a 1d-array
                     (list of values) or a 2d-array of shape N x 2
                     (list of (x, y) pairs). Nested lists can be used
                     instead of arrays.
    @param filename: the name of the output file
    @type filename: C{str}
    @param separator: the contents of the line that is written between
                      two datasets
    @type separator: C{str}
    """
    file = TextFile(filename, 'w')
    nsets = len(datasets)
    for i in range(nsets):
        d = Numeric.array(list(datasets[i]))
        if len(d.shape) == 1:
            d = d[:, Numeric.NewAxis]
        for point in d:
            for number in point:
                file.write(`number` + ' ')
            file.write('\n')
        if (i < nsets-1):
            file.write(separator + '\n')
    file.close()
