大约有 48,000 项符合查询结果（耗时：0.0290秒） [XML]
How to return a part of an array in Ruby?
...", "c" ]
a[1..3] #=> [ "b", "c", "d" ]
a[4..7] #=> [ "e" ]
a[6..10] #=> nil
a[-3, 3] #=> [ "c", "d", "e" ]
# special cases
a[5] #=> nil
a[6, 1] ...
How can I delete one element from an array by value
...
490
I think I've figured it out:
a = [3, 2, 4, 6, 3, 8]
a.delete(3)
#=> 3
a
#=> [2, 4, 6, 8...
How do I sort one vector based on values of another
...
answered Oct 14 '09 at 21:47
Ian FellowsIan Fellows
16k1010 gold badges4444 silver badges6363 bronze badges
...
How to drop columns by name in a data frame
... function. For example :
R> df <- data.frame(x=1:5, y=2:6, z=3:7, u=4:8)
R> df
x y z u
1 1 2 3 4
2 2 3 4 5
3 3 4 5 6
4 4 5 6 7
5 5 6 7 8
Then you can use the which function and the - operator in column indexation :
R> df[ , -which(names(df) %in% c("z","u"))]
x y
1 1 2
2 2 3
3 3 4...
List of lists changes reflected across sublists unexpectedly
...
14 Answers
14
Active
...
How can I sort a dictionary by key?
What would be a nice way to go from {2:3, 1:89, 4:5, 3:0} to {1:89, 2:3, 3:0, 4:5} ?
I checked some posts but they all use the "sorted" operator that returns tuples.
...
Numpy: Divide each row by a vector element
...e is the doc.
– sazary
Apr 8 '15 at 4:10
2
a visual example
– PlsWork
...
Iterate a list with indexes in Python
...
>>> a = [3,4,5,6]
>>> for i, val in enumerate(a):
... print i, val
...
0 3
1 4
2 5
3 6
>>>
share
|
improve this...
Shuffle two list at once with same order
...
answered Apr 25 '14 at 9:45
sshashank124sshashank124
26.6k77 gold badges5353 silver badges6666 bronze badges
...
finding and replacing elements in a list
...
>>> a= [1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1]
>>> for n, i in enumerate(a):
... if i == 1:
... a[n] = 10
...
>>> a
[10, 2, 3, 4, 5, 10, 2, 3, 4, 5, 10]
...