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Python creating a dictionary of lists
...s import defaultdict
>>> d = defaultdict(list)
>>> a = ['1', '2']
>>> for i in a:
... for j in range(int(i), int(i) + 2):
... d[j].append(i)
...
>>> d
defaultdict(<type 'list'>, {1: ['1'], 2: ['1', '2'], 3: ['2']})
>>> d.items()
[(1, ['1']), (...
Extract elements of list at odd positions
...
Solution
Yes, you can:
l = L[1::2]
And this is all. The result will contain the elements placed on the following positions (0-based, so first element is at position 0, second at 1 etc.):
1, 3, 5
so the result (actual numbers) will be:
2, 4, 6
Exp...
Pandas get topmost n records within each group
...
195
Did you try df.groupby('id').head(2)
Ouput generated:
>>> df.groupby('id').head(2)...
Remove duplicated rows using dplyr
...
139
Note: dplyr now contains the distinct function for this purpose.
Original answer below:
li...
What are the GCC default include directories?
...
191
In order to figure out the default paths used by gcc/g++, as well as their priorities, you nee...
How to count the frequency of the elements in an unordered list?
...
1
2
Next
155
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What is the difference between Gemfile and Gemfile.lock in Ruby on Rails
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163
The Gemfile is where you specify which gems you want to use, and lets you specify which versio...
MySQL: What's the difference between float and double?
...
106
They both represent floating point numbers. A FLOAT is for single-precision, while a DOUBLE is...
How to get a specific output iterating a hash in Ruby?
...uts "#{key}-----"
puts array
end
Regarding order I should add, that in 1.8 the items will be iterated in random order (well, actually in an order defined by Fixnum's hashing function), while in 1.9 it will be iterated in the order of the literal.
...
while (1) vs. while(True) — Why is there a difference (in python 2 bytecode)?
Intrigued by this question about infinite loops in perl: while (1) Vs. for (;;) Is there a speed difference? , I decided to run a similar comparison in python. I expected that the compiler would generate the same byte code for while(True): pass and while(1): pass , but this is actually not the c...