import numpy as np
from tempfile import NamedTemporaryFile as Tmp

def load_csv_file(fname, *args, **kargs):
    f = open(fname)
    data = np.genfromtxt(f, delimiter=",", comments="#",
                         *args, **kargs)
    f.close() # don't leak file handles
    return data

def load_csv_file_fast(fname):
    data = np.loadtxt(fname, delimiter=",")
    return data

def load_binary_file(fname, dtype='float32', modify=False):
    data = np.memmap(fname, dtype=dtype,
                     mode='r+' if modify else 'c')
    return data

def write_csv_file(fname, rows, header=None, width=None,
                   break_col=None):
    if fname is None:
        f = Tmp()
    else:
        f = open(fname, 'w')
    if width:
        fmt = "%%%ds" % width
    else:
        fmt = "%s"

    if header:
        f.write('#')
        f.write(", ".join([fmt % str(x) for x in header]))
        f.write('\n')
    last_row = None
    for row in rows:
        # Insert extra line breaks for Gnuplot plot3d plotting whenever
        # the value of break_col changes.
        if not last_row is None and not break_col is None:
            if last_row[break_col] != row[break_col]:
                f.write('\n')
        f.write(' ')
        f.write(", ".join([fmt % str(x) for x in row]))
        f.write('\n')
        last_row = row
    if fname is None:
        # keep it open
        f.flush()
        return f
    else:
        f.close()

def select(keep, rows):
    ok_rows = np.zeros(len(rows), dtype=bool)
    for i, row in enumerate(rows):
        ok_rows[i] = keep(row)
    return rows[ok_rows]