Selecting columns

select-columns.py

foo.py  select-column.py                                                                                                                                                                                                                                                                                                                                                                                                                                                                  X
values = [
  [1, 10, 20, 30, 40],
  [2, 10, 21, 31, 41],
  [3, 11, 22, 32, 42],
  [4, 10, 23, 33, 43],
]

def matches_10(row):
  return row[1] == 10

matches_10 = lambda row: row[1] == 10

def index_is(idx, value):
  return lambda row: row[idx] == value

filtered = filter(lambda row: row[1] == 10, values)

def my_filter(predicate, values):
  results = []

  for value in values:
    if predicate(value):
      results.append(value)

  return results

filtered2 = [row for row in values if row[1] == 10]

print filtered2

print filter(index_is(1, 10), values)

# How we get to things like index_is

# 1

def specific(values):
  results = []
  for row in values:
    if row[1] == 10:
      results.append(row)

  return results

# 2 - Generic on predicated

def my_filter_2(predicate, values):
  results = []
  for row in values:
    if predicate(row):
      results.append(row)

  return results

def matches_10(row):
  return row[1] == 10

specific = my_filter_2(matches_10, values)

# 3 - generic on matches_10

def build_predicate_equals_at(idx, value):
  return lambda row: row[idx] == value


class Person:
  get_name = lambda self: 'Danny'

dan = Person()

print dan.get_name()
print Person.get_name(Person())