大约有 42,000 项符合查询结果（耗时：0.0428秒） [XML]
Pandas dataframe get first row of each group
...;> 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 second
4 5 first
5 6...
What is the smallest possible valid PDF?
...lt;/Type/Catalog/Pages 2 0 R>>endobj 2 0 obj<</Type/Pages/Kids[3 0 R]/Count 1>>endobj 3 0 obj<</Type/Page/MediaBox[0 0 3 3]>>endobj
xref
0 4
0000000000 65535 f
0000000010 00000 n
0000000053 00000 n
0000000102 00000 n
trailer<</Size 4/Root 1 0 R>>
startxref
1...
Joda-Time: what's the difference between Period, Interval and Duration?
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3 classes are needed because they represent different concepts so it is a matter of picking the appropriate one for the job rather than of relative performance. From the documentation with comments added by me in italics:
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Python, compute list difference
...
373
If the order does not matter, you can simply calculate the set difference:
>>> set([...
How can I multiply all items in a list together with Python?
...t takes
a list of numbers and multiplies them together. Example:
[1,2,3,4,5,6] will give me 1*2*3*4*5*6 . I could really use your help.
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“Unicode Error ”unicodeescape" codec can't decode bytes… Cannot open text files in Python 3 [duplica
I am using python 3.1, on a windows 7 machines. Russian is the default system language, and utf-8 is the default encoding.
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Python assigning multiple variables to same value? list behavior
...es are naming the same object, use the is operator:
>>> a=b=c=[0,3,5]
>>> a is b
True
You then ask:
what is different from this?
d=e=f=3
e=4
print('f:',f)
print('e:',e)
Here, you're rebinding the name e to the value 4. That doesn't affect the names d and f in any way.
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Finding median of list in Python
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Python 3.4 has statistics.median:
Return the median (middle value) of numeric data.
When the number of data points is odd, return the middle data point.
When the number of data points is even, the median is interpolated b...
Pickle incompatibility of numpy arrays between Python 2 and 3
I am trying to load the MNIST dataset linked here in Python 3.2 using this program:
7 Answers
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Read stream twice
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Captain Man
5,26733 gold badges3636 silver badges6161 bronze badges
answered Feb 29 '12 at 14:59
Paul GrimePaul Grime
...