Getting the max value from dictionary

Question

So these is how my key value looks like

    dict_info = {}
    dict_info['math 12345'] = 10
    dict_info['math 1234'] = 2
    dict_info['math 123'] = 1
    dict_info['SCI 124'] = 16
    dict_info['SCI 345'] = 2

So there I have five different dictionaries. However what I want to do is make sure I compare the first letter before space for instance I have 3 math there and 2 SCI. I just want to get the highest value of 10 which represents MATH 12345. And get 16 which represents SCI 124 and skip the rest. So all I want is the highest value of classes called math and SCI. And get rid of the ones that is less in value. So far my code looks like this. I couldn't figure the syntax.

def check_if_works():
    import operator
    dict_info = {}
    dict_info['math 12345'] = 10
    dict_info['math 1234'] = 2
    dict_info['math 123'] = 1
    dict_info['SCI 124'] = 16
    dict_info['SCI 345'] = 2
    for key, value in dict_info.iteritems():
        arr = key.split(' ')
        class_first_letters_only = arr[0]
        if class_first_letters_only == arr[0]:



check_if_works()

@user161151 Here is the code but it prints me all the duplicates in my json file.

for key,value in new_dictionary.iteritems():
                                            #print key
                                            k = key.split()[0]
                                            full_info = k + ' ' + key.split()[-1]
                                            print full_info
                                            if ans.get(k,0) < value:
                                                ans[k] = value

                                        #print new_dictionary
                                                sort_info = sorted(ans.items(), key=itemgetter(1,0), reverse=True)
                                                first_20 = sort_info[:20]       

        with open('output_1.json','wb') as outfile:
                json.dump(first_20,outfile,indent=4)

I'd like to also as for my output would want full key name instead of just prefix like MATH i'd want MATH 12345 : 16. Also I'd like to save my output to a json file where it's sorted from max to minimum value pair. @Jankos Frankas

for key, value in new_dictionary.iteritems():
                                            try:
                                                if result[key.split()[0]] < value:
                                                    result[key.split()[0]] = value
                                                    keys[key.split()[0]] = key
                                            except KeyError:
                                                result[key.split()[0]] = value
                                                keys[key.split()[0]] = key
                                        #replace the key prefixes with full length key
                                        for key in keys.keys():
                                            result[keys[key]] = result.pop(key)
                                        #return result
                        with open('output_check_123.json','wb') as outfile:
                            outfile.write(json.dumps(new_dictionary,indent=4))

There's the code.

Answer 1

Returns the maximum values of every unique first word in the keys of dict_info as a dictionary of the key with the maximum value corresponding to that first word in dict_info .

def get_max_groups(dict_info):
    result = {}
    for key, value in dict_info.iteritems():
        sub_key = key.split()[0]
        match_keys = filter(lambda ikey: ikey.split()[0] == sub_key, result)
        if not match_keys:
            result[key] = value
            continue
        m = match_keys[0]
        if result[m] < value:
            del result[m]
            ans[key] = value
    return ans

Answer 2

Use max with some list comprehension :

dict_info = {}
dict_info['math 12345'] = 10
dict_info['math 1234'] = 2
dict_info['math 123'] = 1
dict_info['SCI 124'] = 16
dict_info['SCI 345'] = 2

def check_if_works(dictionary):
    math_max = max([dictionary[key] for key in dictionary if key.startswith('math')])
    sci_max = max([dictionary[key] for key in dictionary if key.startswith('SCI')])
    return math_max, sci_max


print check_if_works(dict_info)

Answer 3

try this:

def check_if_works():
    import operator
    dict_info = {}
    dict_info['math 12345'] = 10
    dict_info['math 1234'] = 2
    dict_info['math 123'] = 1
    dict_info['SCI 124'] = 16
    dict_info['SCI 345'] = 2
    result={}
    for key, value in dict_info.iteritems():
        try:
            if result[key.split()[0]] < value:
                result[key.split()[0]] = value
        except KeyError:
            result[key.split()[0]] = value

    return result



dict_info = check_if_works()
print dict_info

now dict_info equals:

{'SCI': 16, 'math': 10}

if you want the full length key, not only the "prefix" use this code:

def check_if_works():
    import operator
    dict_info = {}
    dict_info['math 12345'] = 10
    dict_info['math 1234'] = 2
    dict_info['math 123'] = 1
    dict_info['SCI 124'] = 16
    dict_info['SCI 345'] = 2
    result={}
    keys = {}
    for key, value in dict_info.iteritems():
        try:
            if result[key.split()[0]] < value:
                result[key.split()[0]] = value
                keys[key.split()[0]] = key
        except KeyError:
            result[key.split()[0]] = value
            keys[key.split()[0]] = key
    #replace the key prefixes with full length key
    for key in keys.keys():
        result[keys[key]] = result.pop(key)
    return result



dict_info = check_if_works()
print dict_info

resul:

{'math 12345': 10, 'SCI 124': 16}

Answer 4

def check_duplicates(dict_info):
    import operator

    result={}
    keys = {}
    for key, value in dict_info.iteritems():
        try:
            #print result[key.split()[0]]
            if result[key.split()[0]] < value:
                result[key.split()[0]] = value
                keys[key.split()[0]] = key
        except KeyError:
            result[key.split()[0]] = value
            keys[key.split()[0]] = key
    #replace the key prefixes with full length key
    for key in keys.keys():
        result[keys[key]] = result.pop(key)
    return result

This worked great thanks to @Jankos. I added an argument called dict_info where I can just use this function to make it work under my main script which has the same formatting of dictionary as presented. Now it works flawlessly, thank you!