Styjun

I have a tuple of input integer values, and a value of high. I want to loop through and pull out pairs of the first instance of a value in the tuple that is >= high, and then first value that is < high. An example might help:

Keep only the first high or first low of each repeating high or low

For instance, if max == 100, and the input is (102, 109, 120, 80, 40, 30, 200, 90)

output should be [[102, 80], [200, 90]]

items = (102, 109, 120, 80, 40, 30, 200, 90)
high = 100
started = False # Used to ensure we start with high values first
currently_on_highs = True
first_val_high = True
first_val_low = True
transitions = []
inner_transition = []

for item in items:
 if item >= high:
 started = True
 currently_on_highs = True
 if first_val_high:
 first_val_high = False
 first_val_low = True
 inner_transition.append(item)
 else:
 if started:
 currently_on_highs = False
 if first_val_low:
 first_val_high = True
 first_val_low = False
 inner_transition.append(item)
 transitions.append(inner_transition)
 inner_transition = []

print(transitions)

Here's a much better result after the suggestion from @michael-butscher

items = (102, 109, 120, 80, 40, 30, 200, 90)
high = 100
in_high = False
transitions = []
inner_transition = []

for item in items:
 if item >= high and not in_high:
 in_high = True
 inner_transition.append(item)
 elif item < high and in_high:
 in_high = False
 inner_transition.append(item)
 transitions.append(inner_transition)
 inner_transition = []

print(transitions)

You can easily do this with zip by offsetting the elements by one entry to compare each of them with their predecessor:

items = (102, 109, 120, 80, 40, 30, 200, 90)
high = 100
bounds = [ num for prev,num in zip((high-1,)+items,items) if (num<high)^(prev<high) ] 
result = list(zip(bounds[::2],bounds[1::2]))
print(result) # [(102, 80), (200, 90)]

Here you go:

items = (102, 109, 120, 80, 40, 30, 200, 90)
high = 100

ret = []
findh = True
for i in items:
 if findh and i >= high:
 findh = False
 ret.append([i])
 elif not findh and i < high:
 findh = True
 ret[-1].append(i)

print(ret)

Explanation:

• 
  ret = [] what we will add the pairs to


• 
  findh = True whether or not we should look for a higher value


• 
  if findh and i >= high: if we are looking higher and it is higer
  
  
  • 
    findh = False look lower in future
  
  
  • 
    ret.append([i]) add another list to our master list, with just this value in
  
  


• 
  elif not findh and i < high: if we are looking lower and it is lower
  
  
  • 
    findh = True look higher in future
  
  
  • 
    ret[-1].append(i) add this value to the last list in the master list
  
  

A first step could be creating a list of all "switch" values:

items = (102, 109, 120, 80, 40, 30, 200, 90)
high = 100

res = []
last = high-1
for x in items:
 if last < high <= x or x <= high < last: 
 res.append(x) 
 last = x

then you can build the pairs:

res = [(res[i], res[i+1]) for i in range(0, len(res), 2)]