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Pandas get topmost n records within each group
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Did you try df.groupby('id').head(2)
Ouput generated:
>>> df.groupby('id').head(2)
id value
id
1 0 1 1
1 1 2
2 3 2 1
4 2 2
3 7 3 1
4 8 4 1
(Keep in mind that you might nee...
Using jQuery to compare two arrays of Javascript objects
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278
There is an easy way...
$(arr1).not(arr2).length === 0 && $(arr2).not(arr1).length ==...
How to change the indentation width in emacs javascript mode
I'd like to use 2 spaces for my indents instead of 4. I can change the default behavior of C mode using:
9 Answers
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二维码的生成细节及原理 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...一下二维码一共有40个尺寸。官方叫版本Version。Version 1是21 x 21的矩阵，Version 2是 25 x 25的矩阵，Version 3是29的尺寸，每增加一个version，就会增加4的尺寸，公式是：(V-1)*4 + 21（V是版本号） 最高Version 40，(40-1)*4+21 = 177，所以最高是...
Pandas groupby: How to get a union of strings
...s+')
In [5]: df
Out[5]:
A B C
0 1 0.749065 This
1 2 0.301084 is
2 3 0.463468 a
3 4 0.643961 random
4 1 0.866521 string
5 2 0.120737 !
In [6]: df.dtypes
Out[6]:
A int64
B float64
C object
dtype: object
When you apply your own functi...
How can I redirect the output of the “time” command?
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edited Mar 9 '10 at 12:37
Motti
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answe...
PHP Foreach Pass by Reference: Last Element Duplicating? (Bug?)
... $item is still a reference to some value which is also being used by $arr[2]. So each foreach call in the second loop, which does not call by reference, replaces that value, and thus $arr[2], with the new value.
So loop 1, the value and $arr[2] become $arr[0], which is 'foo'.
Loop 2, the value and ...
How do I delete rows in a data frame?
...he '-' operator.
So, assuming the data.frame is called myData:
myData[-c(2, 4, 6), ] # notice the -
Of course, don't forget to "reassign" myData if you wanted to drop those rows entirely---otherwise, R just prints the results.
myData <- myData[-c(2, 4, 6), ]
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How to set a Timer in Java?
How to set a Timer, say for 2 minutes, to try to connect to a Database then throw exception if there is any issue in connection?
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How to use the 'sweep' function
...ation defined by FUN.
For instance, if you want to add 1 to the 1st row, 2 to the 2nd, etc. of the matrix you defined, you will do:
sweep (M, 1, c(1: 4), "+")
I frankly did not understand the definition in the R documentation either, I just learned by looking up examples.
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