def pair_duration_sequence_elements_with_input_pair_values(duration_sequence, input_pairs):
r'''Pair `duration_sequence` elements with the values of `input_pairs`:
::
>>> duration_sequence = [10, 10, 10, 10]
>>> input_pairs = [('red', 1), ('orange', 18), ('yellow', 200)]
::
>>> sequencetools.pair_duration_sequence_elements_with_input_pair_values(
... duration_sequence, input_pairs)
[(10, 'red'), (10, 'orange'), (10, 'yellow'), (10, 'yellow')]
Returns a list of ``(element, value)`` output pairs.
The `input_pairs` argument must be a list of ``(value, duration)`` pairs.
The basic idea behind the function is model which input pair
value is in effect at the start of each element in `duration_sequence`.
'''
from abjad.tools import sequencetools
assert sequencetools.all_are_numbers(duration_sequence)
assert sequencetools.all_are_pairs(input_pairs)
output_pairs = []
current_element_start = 0
current_input_pair_index = 0
current_input_pair = input_pairs[current_input_pair_index]
current_input_pair_value = current_input_pair[0]
current_input_pair_duration = current_input_pair[-1]
current_input_pair_start = 0
current_input_pair_stop = current_input_pair_start + current_input_pair_duration
for element in duration_sequence:
while current_input_pair_stop <= current_element_start:
current_input_pair_index += 1
current_input_pair = input_pairs[current_input_pair_index]
current_input_pair_value = current_input_pair[0]
current_input_pair_duration = current_input_pair[-1]
current_input_pair_start = current_input_pair_stop
current_input_pair_stop += current_input_pair_duration
output_pair = (element, current_input_pair_value)
output_pairs.append(output_pair)
current_element_start += element
return output_pairs
def test_sequencetools_all_are_pairs_02():
assert not all_are_pairs('foo')
assert not all_are_pairs(1.5)
assert not all_are_pairs([1, 2])
assert not all_are_pairs([(1, 2), (3, 4), (5, 6, 7)])
def test_sequencetools_all_are_pairs_01():
assert all_are_pairs([(1, 2), (3, 4), (5, 6), (7, 8)])
assert all_are_pairs([])
