Python List Of Dictionaries By Loops

I have 2 python list of dictionaries: [ {'index':'1','color':'red'}, {'index':'2','color':'blue'}, {'index':'3','color':'green'} ] and [ {'device':'1','name':'x'},

Solution 1:

If you want only print the resulting dictionaries, uncomment the print statement (and comment the following 2).

d1 = [
    {'index':'1','color':'red'},
    {'index':'2','color':'blue'},
    {'index':'3','color':'green'}
]

d2 = [
    {'device':'1','name':'x'},
    {'device':'2','name':'y'},
    {'device':'3','name':'z'}
]


result_list = []
for dict1 in d1:
    merged_dict = dict1.copy()
    for dict2 in d2:
        merged_dict.update(dict2)
#       print(merged_dict)
        result_list.append(merged_dict.copy())

print(result_list)

The result:

[{'name': 'x', 'device': '1', 'color': 'red', 'index': '1'}, {'name': 'y', 'device': '2', 'color': 'red', 'index': '1'}, {'name': 'z', 'device': '3', 'color': 'red', 'index': '1'}, {'name': 'x', 'device': '1', 'color': 'blue', 'index': '2'}, {'name': 'y', 'device': '2', 'color': 'blue', 'index': '2'}, {'name': 'z', 'device': '3', 'color': 'blue', 'index': '2'}, {'name': 'x', 'device': '1', 'color': 'green', 'index': '3'}, {'name': 'y', 'device': '2', 'color': 'green', 'index': '3'}, {'name': 'z', 'device': '3', 'color': 'green', 'index': '3'}]

Solution 2:

If you just want to merge the n.-th dict of the first list with the n.-th dict of the second list you can do something like this:

a = [
    {'index':'1','color':'red'},
    {'index':'2','color':'blue'},
    {'index':'3','color':'green'}
]

b = [
    {'device':'1','name':'x'},
    {'device':'2','name':'y'},
    {'device':'3','name':'z'}
]

defmerge(x,y):
    z = x.copy()
    z.update(y)
    return z

>>> [merge(x,y) for x,y inzip(a,b)]

[{'color': 'red', 'device': '1', 'index': '1', 'name': 'x'},
 {'color': 'blue', 'device': '2', 'index': '2', 'name': 'y'},
 {'color': 'green', 'device': '3', 'index': '3', 'name': 'z'}]

merge(x,y) is a helper function that returns a single dictionary with all contents of x and y.

zip(a,b) returns a list of tuples, where the first element of each tuple is an element of a and the second element is an element of b. This allows to use list comprehensions on two lists in parallel.