# Design Example
# Quantitative Analysis: Version 2
# For demonstration purposes only

import matplotlib.pyplot as plt

def read_measurements(filename):
    """
    Returns a dictionary mapping column names to a tuple of all of the values in
    filename corresponding to that column name. Assumes the first line of the
    file is column names.
    """
    datafile = open(filename)
    row_list = [row.split() for row in datafile]
    datafile.close()

    # print "row_list:", row_list
    raw_columns = zip(*row_list)

    # raw_columns = []
    # for i in range(len(row_list[0])):
    #     raw_columns.append([])
    #
    # for row in row_list:
    #     for i in range(len(row)):
    #         raw_columns[i].append(row[i])
    #
    # for i in range(len(row)):
    #     raw_columns[i] = tuple(raw_columns[i])

    print "raw_columns:", raw_columns

    columns = dict([(col[0], col[1:]) for col in raw_columns])

    # columns = {}
    # for col in raw_columns:
    #     columns[col[0]] = col[1:]

    # print "read_measurements returns:", columns
    return columns

def tofloat(measurements, columnname):
    """
    measurements is a dictionary
    columnname is a key in measurements
    Extract the specified column of values from the given measurements
    Returns a list of values in that column, converted to floats
    """
    float_list = [float(x) for x in measurements[columnname]]

    # float_list = []
    # for x in measurements[columnname]:
    #     float_list.append(float(x))

    # print "tofloat(", columnname, ") returns:", float_list
    return float_list

def STplot(measurements):
    """
    Given a dictionary mapping column names to a tuple of values in that column,
    plots salt vs. temp.
    """
    xs = tofloat(measurements, "salt")
    ys = tofloat(measurements, "temp")
    plt.plot(xs, ys)
    plt.xlabel("salt")
    plt.ylabel("temp")
    plt.show()

def minimumO2(measurements):
    """
    Returns the minimum value of the oxygen measurement.
    """
    return min(tofloat(measurements, "o2"))

# Sample client calls:
col_to_data_dict = read_measurements("sample_quant.txt")
STplot(col_to_data_dict)
print "minimum o2 in file:", minimumO2(col_to_data_dict)