About web scraping in python [closed] - python

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There are two major variables (calls and puts), and several sub-variables (e.g. bid, change, time etc.) For example, if there are total 5 data points. I know how to do separately:
data[u'options'][0]["calls"][0]["change"]['fmt'], data[u'options'][0]["calls"][1]["change"]['fmt'], data[u'options'][0]["calls"][2]["change"]['fmt'], data[u'options'][0]["calls"][3]["change"]['fmt'],data[u'options'][0]["calls"][4]["change"]['fmt']
but that spend too much time. I wonder how to choose multiple items in one code.

You can do this with a little bit of list comprehension if I understand your question properly.
For each value in data["options"][0]["calls"], it adds that value's ["change"]["fmt"] value to the list.
d = [call["change"]["fmt"] for call in data["options"][0]["calls"]]
If you want a list of EACH value from every set of options, you could do it like so:
d = [[call["change"]["fmt"] for call in option["calls"]] for option in data["options"]]
and now you can say
for option in d:
for call in option:
print(call)

[data[u'options'][0]["calls"][i]["change"]['fmt'] for i in range(5)]
I don't quite understand your problem, is this what you're after?

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Using a Python dictionary value in a calculation [closed]

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I have some Python code that takes user input for mass and diameter of an object. Those data parameters I later use in a calculation formula. Instead of having the user input those two values, I now have a dictionary that stores the values. How can I now have those values extracted from the dictionary and placed into the calculation formula? I'm very new to Python and trying to figure out if this done via a while loop or defining an function within a while loop, etc.
Thanks.

When to use Lists, Sets, Dictionaries, or tuples in python? [closed]

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I'm new to python, and I'm a bit confused about the use cases of data types in python
Can someone please explain in detail when to use each data type, with an example if possible
Thank you.
Lists are used when you have data you want to further modify, alter like sorting and all.
Dictionary is used when you have to sets of data where data of the first set corresponds to data of other set. And the position of the data doesn't matter only the relation of the two sets matters.
A tuple is used when position of the data is very important and you don't want to alter the position throughout.

What are the various ways to iterate over map() function other than list [closed]

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Suppose I have the some code in which I used map() function.
I know I can later print it by converting it to list just like this :
get_something = map(some_function, some_list)
print(list(get_something))
But Is there any way other than list. I mean what if I want to print not as list but line by line and don't want to use for loop every now and then?
Why dont you try this:
print(*map(some_function, some_list),sep='\n')
By this print() will refer to map object and will print values with \n as a separator

Free function that gives a lexicographically bigger string each time [closed]

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I am implementing a toy db, and I need a free function that gives me a lexicophgraically bigger string each time it's called. It's for naming segment files.
Let's assume I have a max of 1000 files, and I'd prefer if the string was less than 10 characters long.
Could someone give me the easiest example of such a function in python? I'd really like to be a free function as I don't want to introduce complexity with state.
A function that returns a different value each time you call it will have to keep some sort of state. However, defining a generator makes that relatively simple to manage. Specifically, itertools.count will produce an infinite stream of increasing integers; you just need to produce a suitable string from each integer.
from itertools import count
next_label = map("{:010}".format, count()).__next__
Then
>>> next_label()
'0000000000'
>>> next_label()
'0000000001'
>>> next_label()
'0000000002'
and so on, for as many times as you need to call next_label.

Convert < > from string [closed]

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I want to get < from a string that contains the character.
So what I want to do is:
magic_function('<') = <
in order to make. For example:
1 magic_function('<') 3
I expect, of course, that the program returns True
This isn’t possible with specifically what you want. A function returns an object, not an operator. I’m not sure what your main intention is here but you might want to rethink your architecture.
What you can do (but what I don’t recommend) is using eval() like so:
eval(“1 < 3”)
But there are many resources online about why eval is “evil”: to sum them up, if you don’t know what your data source is, then you could be performing unexpected operations which you might not want.

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