Max Value within a List of Lists of Tuple

Question

I have a problem to get the highest Value in a dynamic List of Lists of Tuples.
The List can looks like this:

adymlist = [[('name1',1)],[('name2',2),('name3',1), ...('name10', 20)], ...,[('name m',int),..]]

Now I loop through the List to get the highest Value (integer):

total = {}
y=0 
while y < len(adymlist):
    if len(adymlist) == 1:
         #has the List only 1 Element -> save it in total 
         total[adymlist[y][0][0]] = adymlist[y][0][1]
         y += 1
    else:
         # here is the problem
         # iterate through each lists to get the highest Value
         # and you dont know how long this list can be
         # safe the highest Value in total f.e. total = {'name1':1,'name10':20, ..}

I tried a lot to get the maximum Value but I found no conclusion to my problem. I know i must loop through each Tuple in the List and compare it with the next one but it dont know how to code it correct.

Also I can use the function max() but it doesnt work with strings and integers. f.e. a = [ ('a',5),('z',1)] -> result is max(a) ---> ('z',1) obv 5 > 1 but z > a so I tried to expand the max function with max(a, key=int) but I get an Type Error.

Hope you can understand what I want ;-)

UPDATE

Thanks so far.

If I use itertools.chain(*adymlist) and max(flatlist, key=lambda x: x[1])
I will get an exception like : max_word = max(flatlist, key=lambda x: x[1]) TypeError: 'int' object is unsubscriptable

BUT If I use itertools.chain(adymlist) it works fine. But I dont know how to summate all integers from each Tuple of the List. I need your help to figure it out.

Otherwise I wrote a workaround for itertools.chain(*adymlist) to get the sum of all integers and the highest integer in that list.

chain = itertools.chain(*adymlist)
flatlist = list(chain)
# flatlist = string, integer, string, integer, ...
max_count = max(flatlist[1:len(flatlist):2])
total_count = sum(flatlist[1:len(flatlist):2])
# index of highest integer
idx = flatlist.index(next((n for n in flatlist if n == max_count)))
max_keyword = flatlist[idx-1]

It still does what I want, but isn't it to dirty?

score 16 · Accepted Answer · edited May 23 '17 at 11:58

To clarify, looks like you've got a list of lists of tuples. It doesn't look like we care about what list they are in, so we can simplify this to two steps

Flatten the list of lists to a list of tuples
Find the max value

The first part can be accomplished via itertools.chain (see e.g., Flattening a shallow list in Python)

The second can be solved through max, you have the right idea, but you should be passing in a function rather than the type you want. This function needs to return the value you've keyed on, in this case ,the second part of the tuple

max(flatlist, key=lambda x: x[1])

Correction

I re-read your question - are you looking for the max value in each sub-list? If this is the case, then only the second part is applicable. Simply iterate over your list for each list

A bit more pythonic than what you currently have would like

output = [] 
for lst in lists:
   output.append( max(flatlist, key=lambda x: x[1]) )

or

map(lambda x:  max(x, key=lambda y: y[1]) , lists)

score 4 · Answer 2 · answered Feb 10 '11 at 23:53

As spintheblack says, you have a list of lists of tuples. I presume you are looking for the highest integer value of all tuples.

You can iterate over the outer list, then over the list of tuples tuples like this:

max_so_far = 0
for list in adymlist:
  for t in list:
    if t[1] > max_so_far:
      max_so_far = t[1]
print max_so_far

This is a little bit more verbose but might be easier to understand.

Max Value within a List of Lists of Tuple

UPDATE

2 Answers2