Python combine partially the same Array

Question

I've a 2D array and would like to combine partially similar items.

[
[Red,Blue,Yellow,5]
[Red,Blue,Yellow,10]
[Red,Blue,Green,5]
[Red,Blue,Green,5]
[Red,Blue,Orange,5]
[Red,Blue,Violet,5]
]

I want it to become like this, trimming and creating a unique array

[
[Red,Blue,Yellow,15]
[Red,Blue,Green,10]
[Red,Blue,Orange,5]
[Red,Blue,Violet,5]
]

Edit1: Here's what i did. I've only the basics and would like to have a better version.

newTaskList = []
totalTaskList = []
totalValueList = []
finalTaskList = []

for taskIndex, taskList in enumerate(readTaskList):
    newTaskList = []
    newTaskList.append(taskList[0])
    newTaskList.append(taskList[1])
    newTaskList.append(taskList[2])
    newTaskList.append(taskList[4])


    if(newTaskList not in totalTaskList):
        totalTaskList.append(newTaskList)
        totalValueList.append(float(taskList[3]))

    else:
        for itemIndex, itemList in enumerate(totalTaskList):
            if(itemList[0] == taskList[0] and itemList[1] == taskList[1] and itemList[2] == taskList[2] and itemList[3] == taskList[4]):
                totalValueList[itemIndex] += float(taskList[3])

for taskIndex, task in enumerate(totalTaskList):
    for workType in workTypeList:
        newWorkTypeItem = task[2].replace(" ","_").split("_")
        if len(newWorkTypeItem) > 1:
            task[2] = newWorkTypeItem[0] + " " + newWorkTypeItem[1]

        if(task[1] == workType[0] and task[2] == workType[1]):
            task[2] = workType[2]
            break            
    task.append(totalValueList[taskIndex])
    finalTaskList.append(task)

Please check [SO]: How to create a Minimal, Complete, and Verifiable example (mcve). Hint: this could probably be done in one line of code (excepting imports) using itertools module. — CristiFati
– CristiFati, Commented May 30, 2018 at 8:35
I'd create a defaultdict, use a tuple of the colors as a key, and iterate through, adding all the values with the same keys together. — alkasm
– alkasm, Commented May 30, 2018 at 8:36

Rakesh · Accepted Answer · 2018-05-30 08:41:33Z

1

Using collections Module.

Ex:

from collections import defaultdict
l = [
['Red','Blue','Yellow',5],
['Red','Blue','Yellow',10],
['Red','Blue','Green',5],
['Red','Blue','Green',5],
['Red','Blue','Orange',5],
['Red','Blue','Violet',5],
]

d = defaultdict(int)
for i in l:
    d[tuple(i[:3])] += i[-1]
print [list(k) + [v] for k,v in d.items()]

Output:

[['Red', 'Blue', 'Orange', 5], ['Red', 'Blue', 'Yellow', 15], ['Red', 'Blue', 'Violet', 5], ['Red', 'Blue', 'Green', 10]]

answered May 30, 2018 at 8:41

Rakesh

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2 Comments

Maylin Anne Over a year ago

I knew there's an awesome way in doing it in python and here it is! Thank you so much.

Ontamu Over a year ago

A thing to mention is that the result wouldn't appear in the same order as the original list but if that is not an issue for your purpose you are fine.

Mihai Alexandru-Ionut · Accepted Answer · 2018-05-30 08:40:03Z

1

You can use defaultdict.

result = defaultdict(int)
for col1, col2, col3, value in my_list:
   result[(col1, col2, col3)] += value
result = [list(key) + [value] for key,value in result.items()]
print(result)

Output

[['Red', 'Blue', 'Yellow', 15], ['Red', 'Blue', 'Green', 10], ['Red', 'Blue', 'Orange', 5], ['Red', 'Blue', 'Violet', 5]]

answered May 30, 2018 at 8:40

Mihai Alexandru-Ionut

48.6k14 gold badges106 silver badges132 bronze badges

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