Python data mutation with a for loop and list comprehension: How to be more Pythonic
$begingroup$
I would like to transform a dict of one format into a dict of another format.
The raw_input dict will have the shape:
'key': ['list of strings']
I would like to reformat it into a list of dicts with the following shape:
[
{'key': 'string'},
{'key': 'string'},
...etc for each item in the list of strings
]
My implementation is functional but naive, using a doubly nested for loop:
raw_input = {
'error': ['string 1', 'string2'],
'error2': ['string 3']
}
def return_dict_as_list(raw_input):
mylist =
for foo in raw_input:
for bar in raw_input[item]:
mylist.append( { 'mykey': foo, 'myvalue': bar } )
return mylist
The output is as expected but I can't help but think there's a better way.
I did try a couple of list comprehensions, but the output was not what was desired:
for example this:
elist = [[{'field': item, 'message': msg} for msg in raw[item]] for item in raw]
returns nested lists within a list, which I could unpack but doesn't seem very zen.
here's an online repl with the code:
https://repl.it/repls/UnpleasantBiodegradableSystems
python beginner
asked 41 mins ago
timtim
15015
$endgroup$
add a comment |
$begingroup$
I would like to transform a dict of one format into a dict of another format.
The raw_input dict will have the shape:
'key': ['list of strings']
I would like to reformat it into a list of dicts with the following shape:
[
{'key': 'string'},
{'key': 'string'},
...etc for each item in the list of strings
]
My implementation is functional but naive, using a doubly nested for loop:
raw_input = {
'error': ['string 1', 'string2'],
'error2': ['string 3']
}
def return_dict_as_list(raw_input):
mylist =
for foo in raw_input:
for bar in raw_input[item]:
mylist.append( { 'mykey': foo, 'myvalue': bar } )
return mylist
The output is as expected but I can't help but think there's a better way.
I did try a couple of list comprehensions, but the output was not what was desired:
for example this:
elist = [[{'field': item, 'message': msg} for msg in raw[item]] for item in raw]
returns nested lists within a list, which I could unpack but doesn't seem very zen.
here's an online repl with the code:
https://repl.it/repls/UnpleasantBiodegradableSystems
python beginner
asked 41 mins ago
timtim
15015
$endgroup$
$begingroup$
Shouldfor bar in raw_input[item]:actually befor bar in raw_input[foo]:?
$endgroup$
– Graipher
30 mins ago
$begingroup$
Also, you should make the purpose of your code the title of your question, not what you want out of a review. Have a look at How to Ask.
$endgroup$
– Graipher
19 mins ago
add a comment |
$begingroup$
I would like to transform a dict of one format into a dict of another format.
The raw_input dict will have the shape:
'key': ['list of strings']
I would like to reformat it into a list of dicts with the following shape:
[
{'key': 'string'},
{'key': 'string'},
...etc for each item in the list of strings
]
My implementation is functional but naive, using a doubly nested for loop:
raw_input = {
'error': ['string 1', 'string2'],
'error2': ['string 3']
}
def return_dict_as_list(raw_input):
mylist =
for foo in raw_input:
for bar in raw_input[item]:
mylist.append( { 'mykey': foo, 'myvalue': bar } )
return mylist
The output is as expected but I can't help but think there's a better way.
I did try a couple of list comprehensions, but the output was not what was desired:
for example this:
elist = [[{'field': item, 'message': msg} for msg in raw[item]] for item in raw]
returns nested lists within a list, which I could unpack but doesn't seem very zen.
here's an online repl with the code:
https://repl.it/repls/UnpleasantBiodegradableSystems
python beginner
asked 41 mins ago
timtim
15015
$endgroup$
I would like to transform a dict of one format into a dict of another format.
The raw_input dict will have the shape:
'key': ['list of strings']
I would like to reformat it into a list of dicts with the following shape:
[
{'key': 'string'},
{'key': 'string'},
...etc for each item in the list of strings
]
My implementation is functional but naive, using a doubly nested for loop:
raw_input = {
'error': ['string 1', 'string2'],
'error2': ['string 3']
}
def return_dict_as_list(raw_input):
mylist =
for foo in raw_input:
for bar in raw_input[item]:
mylist.append( { 'mykey': foo, 'myvalue': bar } )
return mylist
The output is as expected but I can't help but think there's a better way.
I did try a couple of list comprehensions, but the output was not what was desired:
for example this:
elist = [[{'field': item, 'message': msg} for msg in raw[item]] for item in raw]
returns nested lists within a list, which I could unpack but doesn't seem very zen.
here's an online repl with the code:
https://repl.it/repls/UnpleasantBiodegradableSystems
python beginner
python beginner
asked 41 mins ago
timtim
15015
asked 41 mins ago
timtim
15015
asked 41 mins ago
timtim
15015
asked 41 mins ago
timtim
15015
asked 41 mins ago
timtim
15015
15015
$begingroup$
Shouldfor bar in raw_input[item]:actually befor bar in raw_input[foo]:?
$endgroup$
– Graipher
30 mins ago
$begingroup$
Also, you should make the purpose of your code the title of your question, not what you want out of a review. Have a look at How to Ask.
$endgroup$
– Graipher
19 mins ago
add a comment |
$begingroup$
Shouldfor bar in raw_input[item]:actually befor bar in raw_input[foo]:?
$endgroup$
– Graipher
30 mins ago
$begingroup$
Also, you should make the purpose of your code the title of your question, not what you want out of a review. Have a look at How to Ask.
$endgroup$
– Graipher
19 mins ago
$begingroup$
Should
for bar in raw_input[item]: actually be for bar in raw_input[foo]:?$endgroup$
– Graipher
30 mins ago
$begingroup$
Should
for bar in raw_input[item]: actually be for bar in raw_input[foo]:?$endgroup$
– Graipher
30 mins ago
$begingroup$
Also, you should make the purpose of your code the title of your question, not what you want out of a review. Have a look at How to Ask.
$endgroup$
– Graipher
19 mins ago
$begingroup$
Also, you should make the purpose of your code the title of your question, not what you want out of a review. Have a look at How to Ask.
$endgroup$
– Graipher
19 mins ago
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
You can at least turn the inner for loop into a list/generator comprehension and use list.extend:
def return_dict_as_list(raw_input):
mylist =
for key, values in raw_input.items():
my_list.extend({'mykey': key, 'myvalue': value} for value in values)
return mylist
Or you can turn it into one list comprehension with two for loops in it (but no nested lists):
def return_dict_as_list(raw_input):
return [{'mykey': key, 'myvalue': value}
for key in raw_input
for value in raw_input[key]]
Another approach is to make it a generator:
def to_list_generator(d):
for key, values in d.items():
for value in values:
yield {'mykey': key, 'myvalue': value}
answered 27 mins ago
GraipherGraipher
24k53585
$endgroup$
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
You can at least turn the inner for loop into a list/generator comprehension and use list.extend:
def return_dict_as_list(raw_input):
mylist =
for key, values in raw_input.items():
my_list.extend({'mykey': key, 'myvalue': value} for value in values)
return mylist
Or you can turn it into one list comprehension with two for loops in it (but no nested lists):
def return_dict_as_list(raw_input):
return [{'mykey': key, 'myvalue': value}
for key in raw_input
for value in raw_input[key]]
Another approach is to make it a generator:
def to_list_generator(d):
for key, values in d.items():
for value in values:
yield {'mykey': key, 'myvalue': value}
answered 27 mins ago
GraipherGraipher
24k53585
$endgroup$
add a comment |
$begingroup$
You can at least turn the inner for loop into a list/generator comprehension and use list.extend:
def return_dict_as_list(raw_input):
mylist =
for key, values in raw_input.items():
my_list.extend({'mykey': key, 'myvalue': value} for value in values)
return mylist
Or you can turn it into one list comprehension with two for loops in it (but no nested lists):
def return_dict_as_list(raw_input):
return [{'mykey': key, 'myvalue': value}
for key in raw_input
for value in raw_input[key]]
Another approach is to make it a generator:
def to_list_generator(d):
for key, values in d.items():
for value in values:
yield {'mykey': key, 'myvalue': value}
answered 27 mins ago
GraipherGraipher
24k53585
$endgroup$
add a comment |
$begingroup$
You can at least turn the inner for loop into a list/generator comprehension and use list.extend:
def return_dict_as_list(raw_input):
mylist =
for key, values in raw_input.items():
my_list.extend({'mykey': key, 'myvalue': value} for value in values)
return mylist
Or you can turn it into one list comprehension with two for loops in it (but no nested lists):
def return_dict_as_list(raw_input):
return [{'mykey': key, 'myvalue': value}
for key in raw_input
for value in raw_input[key]]
Another approach is to make it a generator:
def to_list_generator(d):
for key, values in d.items():
for value in values:
yield {'mykey': key, 'myvalue': value}
answered 27 mins ago
GraipherGraipher
24k53585
$endgroup$
You can at least turn the inner for loop into a list/generator comprehension and use list.extend:
def return_dict_as_list(raw_input):
mylist =
for key, values in raw_input.items():
my_list.extend({'mykey': key, 'myvalue': value} for value in values)
return mylist
Or you can turn it into one list comprehension with two for loops in it (but no nested lists):
def return_dict_as_list(raw_input):
return [{'mykey': key, 'myvalue': value}
for key in raw_input
for value in raw_input[key]]
Another approach is to make it a generator:
def to_list_generator(d):
for key, values in d.items():
for value in values:
yield {'mykey': key, 'myvalue': value}
answered 27 mins ago
GraipherGraipher
24k53585
edited 22 mins ago
answered 27 mins ago
GraipherGraipher
24k53585
answered 27 mins ago
GraipherGraipher
24k53585
answered 27 mins ago
GraipherGraipher
24k53585
24k53585
add a comment |
add a comment |
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$begingroup$
Should
for bar in raw_input[item]:actually befor bar in raw_input[foo]:?$endgroup$
– Graipher
30 mins ago
$begingroup$
Also, you should make the purpose of your code the title of your question, not what you want out of a review. Have a look at How to Ask.
$endgroup$
– Graipher
19 mins ago