大约有 47,000 项符合查询结果（耗时：0.0773秒） [XML]
Numpy: Divide each row by a vector element
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187
Here you go. You just need to use None (or alternatively np.newaxis) combined with broadcastin...
Convert a row of a data frame to vector
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156
When you extract a single row from a data frame you get a one-row data frame. Convert it to a...
Convert numpy array to tuple
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161
>>> arr = numpy.array(((2,2),(2,-2)))
>>> tuple(map(tuple, arr))
((2, 2), (2...
Pandas dataframe get first row of each group
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>>> df.groupby('id').first()
value
id
1 first
2 first
3 first
4 second
5 first
6 first
7 fourth
If you need id as column:
>>> df.groupby('id').first().reset_index()
id value
0 1 first
1 2 first
2 3 first
3 4 seco...
Is it possible to install another version of Python to Virtualenv?
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12 Answers
12
Active
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How do I find the duplicates in a list and create another list with them?
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586
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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']), (...
jQuery map vs. each
...ion you can potentially waste a lot of memory.
For example:
var items = [1,2,3,4];
$.each(items, function() {
alert('this is ' + this);
});
var newItems = $.map(items, function(i) {
return i + 1;
});
// newItems is [2,3,4,5]
You can also use the map function to remove an item from an array...
What does this square bracket and parenthesis bracket notation mean [first1,last1)?
I have seen number ranges represented as [first1,last1) and [first2,last2) .
4 Answers
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Append column to pandas dataframe
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135
It seems in general you're just looking for a join:
> dat1 = pd.DataFrame({'dat1': [9,5]})...