从python numpy数组写入逗号分隔的值

Question

I'm creating a custom file writer. I need to write out the values of my array as comma separated into one line in the file. I could do the following:

def as_csv(array):

    return ','.join([str(i) for i in array]) + '\n'

then:

outfile.write(my_header)
outfile.write(other_stuff)
outfile.write(as_csv(array))

but I wonder if this is the most efficient way to do this, or if there would be a better method using the numpy.array_str or numpy.array_repr methods.

Answer 1

您还可以使用内置的numpy方法np.savetxt ： http : np.savetxt

np.savetxt(outfile, array, delimiter=',')

Answer 2

I haven't tried to use np.savetxt in the context below, perhaps it could be used so long as the file is opened in append mode, but here is the solution for what I was trying to do. However, it may not be the most efficient..

def _as_csv(self, values):
    vals = ','.join([str(i) for i in values])
    return vals + '\n'

def output(self, filename, series_cnt, series_name, series_type, startdate, N, values, step = 1000):
    """ outputs data to a file """

    starttime = startdate

    num_imports = (N / step) + 1

    outfile = open(filename.format(series_cnt, i), 'w')
    outfile.write('#{0},{1},{2},\n'.format('TEST', startdate.strftime('%Y%m%d%H%M%S000'), str(num_imports)))


    for i in range(0, N, step):

        line_start = '/Test/{0},{1},{2},{3},'.format(series_name, series_type, starttime.strftime('%Y%m%d%H%M%S000'), step)
        outfile.write(line_start)
        nxt = i + step
        starttime = starttime + dt.timedelta(hours=step)

        outfile.write(self._as_csv(values[i:nxt]))

        outfile.close()