Difference between revisions of "CompSciHW6"

Latest revision as of 12:50, 21 March 2016

Homework 6 - Due Friday, March 25

1) Create a function that parses the following files:
 a) mat33 = """
1.0 2.0 3.0
-2.0 0.0 1.0
1.0 1.1 1.2
""" # output a matrix
# example function structure
def parse_mat(s):
  mat = [] # build a list of lists
  ...
  return array(mat) # make into an array

 b) csv = """
# time temperature sea_level
0.0, 300.0, 44.5
1.5, 299.5, 44.0
3.0, 299.8, 44.2
4.5, 301.0, 43.9
""" # output a list of strings and a matrix

 c) name_val = """
seed = 1553
name = "test name"
trials = 10
tolerance = 1e-8
""" # output a dictionary

 d) group_data = """
[Group 1]
1 2 3 4 5 6

[Group 2]
4 5 11 14 1

[Group 3]
7 8 9 10 11
""" # output a dictionary of [int]

2) Complete this function by adding a for loop to fill each 
  element of a vector with a function (g(i)):
  from numpy import *
  def vec_from_func(n, g): # int -> (int -> float) -> array
    x = zeros(n, float)
    for ...
    return x

  # example call
  def square_x(x): # int -> float
    return 1.0*x*x

  g_arr = vec_from_func(10, square_x)

3) Complete this function by adding a nested for-loop to fill
   each element of a matrix with a function, u(i,j):
   from numpy import *
   def mat_from_func(n,m, g): # int -> int -> (int -> int -> float) -> array
   M = zeros((n,m), float)
   for ...
     for ...
   return M

Hint: <source lang="python">

1. parse key-value pairs

def get_kv(x): # str -> (str, str)

 n = x.find('=')
 if n < 0:
   raise ValueError
 return x[:n].strip(), x[n+1:].strip()

1. basic parser structure:

def parse_cif(name):

   f = open(name, 'r')
   out = {}
   state = 0
   vals = []
   for line in f.readlines():
       k = line.strip()
       if not k:
           continue
       # test whether line contains useful info.
   return out

</source>