I'm trying to get a single key value pair using dictionary comprehension as an exercise, I have accomplished this using for loops but the best I can do using dictionary comprehension returns an entire dictionary. If I use anything other than 'inner_key01' or 'inner_key02' in the if portion of the below code I get an empty dictionary.
I would like the code to return 'inner_value22'
my_dict = {'inner_key01' :{'inner_key1': 'inner_value1', 'inner_key2': 'inner_value2'},
'inner_key02' :{'inner_key21': 'inner_value21', 'inner_key22': 'inner_value22'}
}
next_dict = {inner_key: inner_value for inner_key, inner_value in my_dict.items() for outer_key, outer_value in my_dict.items()if inner_key == 'inner_key02'}
print(next_dict)
Related
I have a dictionary comprehension that works, however I'm not sure if it is very readable/understandable (since I don't understand it well, but i'm a noob).
Data structures:
dict1 = {'this key 1':['this is a comment','this too','finally this'],
'this key 2':['this is a comment2','this too2','finally this2'],
'this key 3':['this is a comment3','this too3','finally this3']}
list1 = ['BlIb','vILB','vliH']
Desired output:
{'BlIb':{'this key 1':['this is a comment','this too','finally this']},
'vILB':{'this key 2':['this is a comment2','this too2','finally this2']},
'vliH':{'this key 3':['this is a comment3','this too3','finally this3']}}
Dictionary comprehensions:
As I said above, this one works, but I'm not sure how readable it is, or if I completely understand the inner dict comprehension (using 'key' twice)
all_data = {idx:{key:dict1[key]} for idx,key in zip(list1,dict1)}
Would this be the best way to do it? and if so could you explain this part{key:Dict[key]}?
And if not, how would you do it?
I've also tried the below, but just adds all three of the Dict items for each List item
all_data = {idx: {key:value for (key,value) in dict1.items()} for idx in list1}
I am scraping data with scrapetube to get the video IDs of all the videos from a YouTube channel. The scrape code returns a generator object which I have converted to a list of dictionaries containting other dictionaries, lists and string. The scraping code works, but here still some sample data. I am only interested in the string video Id --> see picture for illustration purposes
How to iterate through all the video IDs in the string videoId and save them in a new variable (list or dataframe) for further processing?
import scrapetube
vid = scrapetube.get_channel('UC_zxivooFdvF4uuBosUnJxQ')
type(vid) #generator file
video = next(vid) #extract values from generator & then convert it
videoL = list(vid) #convert it to a list
#code not working
for item in videoL['videoId']:
entry = {}
videoId = item['videoId']
for i in range(len(videoId)):
entry.append(int(videoId[i][0:10]))
#error message: TypeError: list indices must be integers or slices, not str
I used code snippet from this post but can't seem to make it work.
It's helpful when you know the terminology so let's go through it step by step.
What is a generator?
A generator, like it's name implies, generates values on demand.
Their usefulness in this case is that if you don't want to have all the data in memory, you only iterate over one generated value at a time and only extract what you need.
Consider this:
def gen_one_million():
for i in range(0, 1_000_000):
yield i
for i in gen_one_million():
# do something with i
Rather than having a million elements in a list or some container in memory, you only get one at a time. If you want them all in a list it's very easy to do with list(gen_one_million()) but you're not tied to having them all in memory if you don't need them.
What is a list and how do I use them?
A list in python is a container represented by brackets []. To access elements in a list you can index into it i = my_list[0] or iterate over it.
for i in my_list:
# do something with i
What is a dict and how do I use them?
A dict is a python key/value container type represented by curly braces and a colon between the key and value. {key: value}
To access values in a dict you can reference the key who's value you want i = my_dict[key] where key is a string or integer or some other hashable type. You can also iterate over it.
for key in my_dict:
# do something with the key
for value in my_dict.values():
# do something with the key
for key, value in my_dict.items():
# do something with the key and value
How does my case fit into all this?
Looking at your sample data it looks like you already have it converted from a generator to a list.
[
{
'videoId': '8vCvSmAIv1s',
'thumbnail': {
'thumbnails': [
{
'url': 'https://i.ytimg.com/vi/8vCvSmAIv1s/hqdefault.jpg?sqp=-oaymwEbCKgBEF5IVfKriqkDDggBFQAAiEIYAXABwAEG&rs=AOn4CLDn3-yb8BvctGrMxqabxa_nH-UYzQ',
'width': 168,
'height': 94}, # etc..
}
]
}
}
]
However, since you just need to iterate over it and access the 'videoID' key in each generated dict, there's no reason to convert.
Just iterate directly over the generator and access the key of each generated dict.
video_ids = []
for item in vid:
video_ids.append(item['videoId'])
Or even better, as a list comprehension.
video_ids = [item['videoId'] for item in vid]
Maybe it is ordinary issue regarding iterating thru a dict. Please find below imovel.txt file, whose content is as follows:
{'Andar': ['primeiro', 'segundo', 'terceiro'], 'Apto': ['101','201','301']}
As you can see this is not a ordinary dictionary, with a key value pair; but a key with a list as key and another list as value
My code is:
#/usr/bin/python
def load_dict_from_file():
f = open('../txt/imovel.txt','r')
data=f.read()
f.close()
return eval(data)
thisdict = load_dict_from_file()
for key,value in thisdict.items():
print(value)
and yields :
['primeiro', 'segundo', 'terceiro'] ['101', '201', '301']
I would like to print a key,value pair like
{'primeiro':'101, 'segundo':'201', 'terceiro':'301'}
Given such txt file above, is it possible?
You should use the builtin json module to parse but either way, you'll still have the same structure.
There are a few things you can do.
If you know both of the base key names('Andar' and 'Apto') you can do it as a one line dict comprehension by zipping the values together.
# what you'll get from the file
thisdict = {'Andar': ['primeiro', 'segundo', 'terceiro'], 'Apto': ['101','201','301']}
# One line dict comprehension
newdict = {key: value for key, value in zip(thisdict['Andar'], thisdict['Apto'])}
print(newdict)
If you don't know the names of the keys, you could call next on an iterator assuming they're the first 2 lists in your structure.
# what you'll get from the file
thisdict = {'Andar': ['primeiro', 'segundo', 'terceiro'], 'Apto': ['101','201','301']}
# create an iterator of the values since the keys are meaningless here
iterator = iter(thisdict.values())
# the first group of values are the keys
keys = next(iterator, None)
# and the second are the values
values = next(iterator, None)
# zip them together and have dict do the work for you
newdict = dict(zip(keys, values))
print(newdict)
As other folks have noted, that looks like JSON, and it'd probably be easier to parse it read through it as such. But if that's not an option for some reason, you can look through your dictionary this way if all of your lists at each key are the same length:
for i, res in enumerate(dict[list(dict)[0]]):
ith_values = [elem[i] for elem in dict.values()]
print(ith_values)
If they're all different lengths, then you'll need to put some logic to check for that and print a blank or do some error handling for looking past the end of the list.
I have a list called rest which contains many dictionaries in a list which is in the format
rest = [{'a':'b','c':'d','e':'f'}, {'a':'g','c':'h','e':'i}, {'a':'j','c':'k','e':'l'}]
Can I get an output as below where I have new as a key inside a dictionary for all the key-value pair except the first key-value pair
output = [{'a':'b','new':{'c':'d','e':'f'}},{'a':'g','new':{'c':'h','e':'i'}},{'a':'j','new':{'c':'k','e':'l'}}]
Is it possible?
You can use the syntax first, *remainder to extract the relevant parts and then create a new dict from them:
def convert(d):
first, *remainder = d.items()
return dict([first, ('new', dict(remainder))])
Then to convert each of the dicts:
output = [convert(d) for d in rest]
Note that this syntax was introduced in Python 3.0 and dictionaries are unordered before Python 3.6 (i.e. the first item is not determined).
I have a large dictionary and I am trying to remove values from keys if they start with certain values. Below is a small example of the dictionary.
a_data = {'78567908': {'26.01.17', '02.03.24', '26.01.12', '04.03.03', '01.01.13', '02.03.01', '01.01.10', '26.01.21'}, '85789070': {'26.01.02', '09.01.04', '02.05.04', '02.03.17', '02.05.01'}, '87140110': {'03.15.25', '03.15.24', '03.15.19'}, '87142218': {'26.17.13', '02.11.01', '02.03.22'}, '87006826': {'28.01.03'}}
After I read in the dictionary, I want to remove values from all keys that start with '26.' or '02.' It is possible that would leave a key with no values (an empty set).
I do have code that works:
exclude = ('26.', '02.')
f_a_data = {}
for k, v in a_data.items():
f_a_data.setdefault(k,[])
for code in v:
print (k, code, not code.startswith(exclude))
if not code.startswith(exclude):
f_a_data[k].append(code)
print('Filtered dict:')
print(f_a_data)
This returns a filtered dict:
Filtered dict:
{'78567908': ['04.03.03', '01.01.13', '01.01.10'], '85789070': ['09.01.04'], '87140110': ['03.15.25', '03.15.24', '03.15.19'], '87142218': [], '87006826': ['28.01.03']}
Question 1: Is this the best way to filter a dictionary?
Question 2: How could i modify the above snippet to return values in a set like the original dict?
Your code is quite all right in complexity terms but can be "pythonized" a little and still remain readable.
My proposal: you can rebuild a dictionary using nested comprehensions and all to test if you should include the values:
a_data = {'78567908': {'26.01.17', '02.03.24', '26.01.12', '04.03.03', '01.01.13', '02.03.01', '01.01.10', '26.01.21'}, '85789070': {'26.01.02', '09.01.04', '02.05.04', '02.03.17', '02.05.01'}, '87140110': {'03.15.25', '03.15.24', '03.15.19'}, '87142218': {'26.17.13', '02.11.01', '02.03.22'}, '87006826': {'28.01.03'}}
exclude = ('26.', '02.')
new_data = {k:{x for x in v if all(s not in x for s in exclude)} for k,v in a_data.items()}
result:
>>> new_data
{'78567908': {'01.01.10', '01.01.13', '04.03.03'},
'85789070': {'09.01.04'},
'87006826': {'28.01.03'},
'87140110': {'03.15.19', '03.15.25', '03.15.24'},
'87142218': set()}
(here using a dictionary comprehension embedding a set comprehension (since you need a set) using a generator comprehension in all)