how to make a Multidimensional Dictionary with multiple keys and value and how to print its keys and values?
from this format:
main_dictionary= { Mainkey: {keyA: value
keyB: value
keyC: value
}}
I tried to do it but it gives me an error in the manufacturer. here is my code
car_dict[manufacturer] [type]= [( sedan, hatchback, sports)]
Here is my error:
File "E:/Programming Study/testupdate.py", line 19, in campany
car_dict[manufacturer] [type]= [( sedan, hatchback, sports)]
KeyError: 'Nissan'
And my printing code is:
for manufacuted_by, type,sedan,hatchback, sports in cabuyao_dict[bgy]:
print("Manufacturer Name:", manufacuted_by)
print('-' * 120)
print("Car type:", type)
print("Sedan:", sedan)
print("Hatchback:", hatchback)
print("Sports:", sports)
Thank you! I'm new in Python.
I think you have a slight misunderstanding of how a dict works, and how to "call back" the values inside of it.
Let's make two examples for how to create your data-structure:
car_dict = {}
car_dict["Nissan"] = {"types": ["sedan", "hatchback", "sports"]}
print(car_dict) # Output: {'Nissan': {'types': ['sedan', 'hatchback', 'sports']}}
from collections import defaultdict
car_dict2 = defaultdict(dict)
car_dict2["Nissan"]["types"] = ["sedan", "hatchback", "sports"]
print(car_dict2) # Output: defaultdict(<class 'dict'>, {'Nissan': {'types': ['sedan', 'hatchback', 'sports']}})
In both examples above, I first create a dictionary, and then on the row after I add the values I want it to contain. In the first example, I give car_dict the key "Nissan" and set it's values to a new dictionary containing some values.
In the second example I use defaultdict(dict) which basically has the logic of "if i am not given a value for key then use the factory (dict) to create a value for it.
Can you see the difference of how to initiate the values inside of both of the different methods?
When you called car_dict[manufacturer][type] in your code, you hadn't yet initiated car_dict["Nissan"] = value, so when you tried to retrieve it, car_dict returned a KeyError.
As for printing out the values, you can do something like this:
for key in car_dict:
manufacturer = key
car_types = car_dict[key]["types"]
print(f"The manufacturer '{manufacturer}' has the following types:")
for t in car_types:
print(t)
Output:
The manufacturer 'Nissan' has the following types:
sedan
hatchback
sports
When you loop through a dict, you are looping through only the keys that are contained in it by default. That means that we have to retrieve the values of key inside of the loop itself to be able to print them correctly.
Also as a side note: You should try to avoid using Built-in's names such as type as variable names, because you then overwrite that functions namespace, and you can have some problems in the future when you have to do comparisons of types of variables.
Related
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 series of dictionaries which each contain the same keys but their values are different i.e Age in dictionary 1 = 2, Age in dictionary 2 = 4 etc etc but they are broadly identical in structure.
what I would like to do is to randomly select one of these dictionaries and then assign specific values with the dictionary to variables. i.e python randomly chooses Dictionary 1 and then I then want to fill the dictAge variable with the age value from Dictionary 1.
import random
dictList = ['myDict', 'otherDict']
mydict = {
'age' : 10,
'other': "dummy data"
}
.
.
.
randomDict = random.choice(dictList)
dictAge = randomDict['age']
print(dictAge)
In the case of the code above what should happen is:
randomDict is assigned a random value from the distList variable (at the top). This sets which dictionary's values will be used going forward.
I next want the dictAge variable to then be assigned the age value from the selected dictionary. In this case (as mydict is was the only dictionary available) it should be assigned the age value of 10.
The error I am getting is:
TypeError: string indices must be integers
I know this is such a common error but my brain can't quite work out what the best solution is.
(Disclaimer: I haven't used python in ages so I know I am doing something really obviously silly but I can't quite work out what to do).
Right now, you are not actually using the definition of your dicts.
This is because dictList is comprised of strings: ['myDict', 'otherDict'].
So, when doing randomDict = random.choice(dictList), randomDict will either be the string 'myDict', or the string 'otherDict'.
Then you are doing randomDict['age'], which means you are trying to slice a string, with a string. As the error suggests, this can't be done and indices can only be ints.
What you want to do, is move the definition of the dictList to be after the definitions of your dicts, and include references to the dicts themselves, not strings. Something like:
mydict = {
'age' : 10,
'other': "dummy data"
}
.
.
.
dictList = [myDict, otherDict]
In the following piece of code:
dictAge = randomDict['age']
You are trying to index the name of dictionary variable (a string) returned by random.choice function.
To make it work you would need to do it using locals:
locals()[randomDict]['age']
or rather correct the dictList to contain the dictionaries instead of their names:
dictList = [myDict, otherDict]
In the latter case please note that myDict and otherDict should be declared before dictList.
I've not ever encountered this type of situation in a Python for loop before.
I have a dictionary of Names (key) and Regions (value). I want to match up each Name with two other names. The matched name cannot be themselves and reversing the elements is not a valid match (1,2) = (2,1). I do not want people from the same Region to be matched together though (unless it becomes impossible).
dict = {
"Tom":"Canada",
"Jerry":"USA",
"Peter":"USA",
"Pan":"Canada",
"Edgar":"France"
}
desired possible output:
[('Tom','Jerry'),('Tom','Peter'),('Jerry','Pan'),('Pan','Peter'),('Edgar','Peter'),('Edgar','Jerry')]
Everyone appears twice, but Jerry and Peter appears more in order for Edgar to have 2 matches with Names from a different region (Jerry and Peter should be chosen randomly here)
Count: Tom: 2, Jerry: 3, Peter: 3, Pan: 2, Edgar: 2
My approach is to convert the names into a list, shuffle them, then create tuple pairs using zip in a custom function. After the function is complete. I use a a for to check for pairings from the same region, if a same pairing region exists, then re-run the custom function. For some reason, when I print the results, I still see pairings between the same regions. What am I missing here?
import random
names=list(dict.keys())
def pairing(x):
random.shuffle(x)
#each person is tupled twice, once with the neighbor on each side
pairs = list(zip(x, x[1:]+x[:1]))
return pairs
pairs=pairing(names) #assigns variable from function to 'pairs'
for matchup in pairs:
if dict[matchup[0]]==dict[matchup[1]]:
break
pairing(names)
pairs=pairing(names)
for matchup in pairs:
print(matchup[0] ,dict[matchup[0]] , matchup[1] , dict[matchup[1]])
Just looking at it, something is clearly broken in the for loop, please help!
I've tried while rather than if in the for loop, but it did not work.
from itertools import combinations
import pandas as pd
import random
dict={'your dictionary'}
#create function to pair names together
def pairing(x):
random.shuffle(x)
#each person is tupled twice, once with the neighbor on each side
pairs = list(zip(x, x[1:]+x[:1]))
for matchup in pairs:
if dict[matchup[0]]==dict[matchup[1]]: #if someone's gym matches their opponent's gym in dictionary, re-run this function
return pairing(x)
return pairs
pairs=pairing(names)
for matchup in pairs:
print(matchup[0] ,dict[matchup[0]] , matchup[1] , dict[matchup[1]])
The trick is to return pairing(x) inside the custom function. This will return new pairings if any elements in the tuple share the same value in the dictionary. If inside the if statement, you go pairing(x) then return pair, it'll return the original tuple list which contains duplicates.
I'm very new in python (I usually write in php). I want to understand how to store information in an associative array, and if you can explain me whats the difference of "tuples", "arrays", "dictionary" and "list" will be wonderful (I tried to read different source but I still not caching it).
So This is my code:
#!/usr/bin/python3.4
import csv
import string
nidless_keys = dict()
nidless_keys = ['test_string1','test_string2'] #this contain the string to
# be searched in linesreader
data = {'type':[],'id':[]} #here I want to store my information
with open('path/to/csv/file.csv',newline="") as csvfile:
linesreader = csv.reader(csvfile,delimiter=',',quotechar="|")
for row in linesreader: #every line in this csv have a url like
#www.test.com/?test_string1&id=123456
current_row_string = str(row)
for needle in nidless_keys:
current_needle = str(needle)
if current_needle in current_row_string:
data[current_needle[current_row_string[-8:]]) += 1 # also I
#need to count per every id how much rows there are.
In conclusion:
my_data_stored = [current_needle][current_row_string[-8]]
current_row_string[-8] is a url which the last 8 digit of the url is an ID.
So the array should looks like this at the end of the script:
test_string1 = 123456 = 20
= 256468 = 15
test_string2 = 123155 = 10
Edit 1:
Which type I need here to store the information?
Can you tell me how to resolve this script?
It seems you want to count how many times an ID in combination with a test string occurs.
There can be multiple ID/count combinations associated with every test string.
This suggests that you should use a dictionary indexed by the test strings to store the results. In that dictionary I would suggest to store collections.Counter objects.
This way, you would have to add a special case when a key in the results dictionary isn't found to add an empty Counter. This is a common problem, so there is a specialized form of dictionary in the collections module called defaultdict.
import collections
import csv
# Using a tuple for the keys so it cannot be accidentally modified
keys = ('test_string1', 'test_string2')
result = collections.defaultdict(collections.Counter)
with open('path/to/csv/file.csv',newline="") as csvfile:
linesreader = csv.reader(csvfile,delimiter=',',quotechar="|")
for row in linesreader:
for key in keys:
if key in row:
id = row[-6:] # ID's are six digits in your example.
# The first index is into the dict, the second into the Counter.
result[key][id] += 1
There is an even easier way, by using regular expressions.
Since you seem to treat every row in a CSV file as a string, there is little need to use the CSV reader, so I'll just read the whole file as text.
import re
with open('path/to/csv/file.csv') as datafile:
text = datafile.read()
pattern = r'\?(.*)&id=(\d+)'
The pattern is a regular expression. This is a large topic in and of itself, so I'll only cover briefly what it does. (You might also want to check out the relevant HOWTO) At first glance it looks like complete gibberish, but it is actually a complete language.
In looks for two things in a line. Anything between ? and &id=, and a sequence of digits after &id=.
I'll be using IPython to give an example.
(If you don't know it, check out IPython. It is great for trying things and see if they work.)
In [1]: import re
In [2]: pattern = r'\?(.*)&id=(\d+)'
In [3]: text = """www.test.com/?test_string1&id=123456
....: www.test.com/?test_string1&id=123456
....: www.test.com/?test_string1&id=234567
....: www.test.com/?foo&id=234567
....: www.test.com/?foo&id=123456
....: www.test.com/?foo&id=1234
....: www.test.com/?foo&id=1234
....: www.test.com/?foo&id=1234"""
The text variable points to the string which is a mock-up for the contents of your CSV file.
I am assuming that:
every URL is on its own line
ID's are a sequence of digits.
If these assumptions are wrong, this won't work.
Using findall to extract every match of the pattern from the text.
In [4]: re.findall(pattern, test)
Out[4]:
[('test_string1', '123456'),
('test_string1', '123456'),
('test_string1', '234567'),
('foo', '234567'),
('foo', '123456'),
('foo', '1234'),
('foo', '1234'),
('foo', '1234')]
The findall function returns a list of 2-tuples (that is key, ID pairs). Now we just need to count those.
In [5]: import collections
In [6]: result = collections.defaultdict(collections.Counter)
In [7]: intermediate = re.findall(pattern, test)
Now we fill the result dict from the list of matches that is the intermediate result.
In [8]: for key, id in intermediate:
....: result[key][id] += 1
....:
In [9]: print(result)
defaultdict(<class 'collections.Counter'>, {'foo': Counter({'1234': 3, '123456': 1, '234567': 1}), 'test_string1': Counter({'123456': 2, '234567': 1})})
So the complete code would be:
import collections
import re
with open('path/to/csv/file.csv') as datafile:
text = datafile.read()
result = collections.defaultdict(collections.Counter)
pattern = r'\?(.*)&id=(\d+)'
intermediate = re.findall(pattern, test)
for key, id in intermediate:
result[key][id] += 1
This approach has two advantages.
You don't have to know the keys in advance.
ID's are not limited to six digits.
A brief summary of the python data types you mentioned:
A dictionary is an associative array, aka hashtable.
A list is a sequence of values.
An array is essentially the same as a list, but limited to basic datatypes. My impression is that they only exists for performance reasons, don't think I've ever used one. If performance is that critical to you, you probably don't want to use python in the first place.
A tuple is a fixed-length sequence of values (whereas lists and arrays can grow).
Lets take them one by one.
Lists:
List is a very naive kind of data structure similar to arrays in other languages in terms of the way we write them like:
['a','b','c']
This is a list in python , but seems very similar to array structure.
However there is a very large difference in the way lists are used in python and the usual arrays.
Lists are heterogenous in nature. This means that we can store any kind of data simultaneously inside it like:
ls = [1,2,'a','g',True]
As you can see, we have various kinds of data within a list and is a valid list.
However, one important thing about them is that we can access the list items using zero based indices. So we can write:
print ls[0],ls[3]
output: 1 g
Dictionary:
This datastructure is similar to a hash map data structure. It contains a (key,Value) pair. An empty dictionary looks like:
dc = {}
Now, to store a key,value pair, e.g., ('potato',3),(tomato,5), we can do as:
dc['potato'] = 3
dc['tomato'] = 5
and we saved the data in the dictionary dc.
The important thing is that we can even store another data structure element like a list within a dictionary like:
dc['list1'] = ls , where ls is the list defined above.
This shows the power of using dictionary.
In your case, you have difined a dictionary like this:
data = {'type':[],'id':[]}
This means that your dictionary will consist of only two keys and each key corresponds to a list, which are empty for now.
Talking a bit about your script, the expression :
current_row_string[-8:]
doesn't make a sense. The index should have been -6 instead of -8 that would give you the id part of the current row.
This part is the id and should have been stored in a variable say :
id = current_row_string[-6:]
Further action can be performed as seen the answer given by Roland.