大约有 48,000 项符合查询结果（耗时：0.0405秒） [XML]
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]
...
Sample random rows in dataframe
...rnorm(20), nrow=10))
> df
X1 X2
1 0.7091409 -1.4061361
2 -1.1334614 -0.1973846
3 2.3343391 -0.4385071
4 -0.9040278 -0.6593677
5 0.4180331 -1.2592415
6 0.7572246 -0.5463655
7 -0.8996483 0.4231117
8 -1.0356774 -0.1640883
9 -0.3983045 0.7157506
10 -0.9060305 2.3234...
how to change default python version?
I have installed python 3.2 in my mac. After I run /Applications/Python 3.2/Update Shell Profile.command , it's confusing that when I type python -V in Terminal it says that Python 2.6.1 , how can I change the default python version?
...
What is Weak Head Normal Form?
...re not in normal form:
1 + 2 -- we could evaluate this to 3
(\x -> x + 1) 2 -- we could apply the function
"he" ++ "llo" -- we could apply the (++)
(1 + 1, 2 + 2) -- we could evaluate 1 + 1 and 2 + 2
Weak head normal form
An expression in weak head normal ...
Why are these numbers not equal?
...
359
General (language agnostic) reason
Since not all numbers can be represented exactly in IEEE f...
Ruby - elegantly convert variable to an array if not an array already
...
153
[*foo] or Array(foo) will work most of the time, but for some cases like a hash, it messes it up...
Print all but the first three columns
...,$i OFS; if(NF) printf "%s",$NF; printf ORS}'
### Example ###
$ echo '1 2 3 4 5 6 7' |
awk '{for(i=4;i<NF;i++)printf"%s",$i OFS;if(NF)printf"%s",$NF;printf ORS}' |
tr ' ' '-'
4-5-6-7
Sudo_O proposes an elegant improvement using the ternary operator NF?ORS:OFS
$ echo '1 2 3 4 5 6 7' |
aw...
How to select the row with the maximum value in each group
...t]$V1]
# Subject pt Event
# 1: 1 5 2
# 2: 2 17 2
# 3: 3 5 2
If you'd like just the first max value of pt:
group[group[, .I[which.max(pt)], by=Subject]$V1]
# Subject pt Event
# 1: 1 5 2
# 2: 2 17 2
# 3: 3 5 2
In this case, it ...
Eclipse RCP Plug-in开发自学教程（Eclipse3.6） - 文档下载 - 清泛网 - ...
Eclipse RCP Plug-in开发自学教程（Eclipse3.6） Eclipse RCP Plug-in本教程素材来源于网络，经过本人的整理、添加以及部分的重写，将原有的Eclipse3.3版本的一些内容完全迁移到Eclipse3.6版本上来。基于开源以...本教程素材来源于网络，经...
How do I use floating-point division in bash?
...d
– Nahuel Fouilleul
Oct 4 '12 at 7:32
4
...