大约有 2,000 项符合查询结果（耗时：0.0168秒） [XML]
Split delimited strings in a column and insert as new rows [duplicate]
...|b,d\n4|e,f"), header = F, sep = "|", stringsAsFactors = F)
df
## V1 V2
## 1 1 a,b,c
## 2 2 a,c
## 3 3 b,d
## 4 4 e,f
s <- strsplit(df$V2, split = ",")
data.frame(V1 = rep(df$V1, sapply(s, length)), V2 = unlist(s))
## V1 V2
## 1 1 a
## 2 1 b
## 3 1 c
## 4 2 a
## 5 2 c...
How to remove empty cells in UITableView? [duplicate]
...
Implemented with swift on Xcode 6.1
self.tableView.tableFooterView = UIView(frame: CGRectZero)
self.tableView.tableFooterView?.hidden = true
The second line of code does not cause any effect on presentation, you can use to check if is hidden or not.
Ans...
How to convert C# nullable int to int
...r are all correct; I just wanted to add one more that's slightly cleaner:
v2 = v1 ?? default(int);
Any Nullable<T> is implicitly convertible to its T, PROVIDED that the entire expression being evaluated can never result in a null assignment to a ValueType. So, the null-coalescing operator ?...
Cosine Similarity between 2 Number Lists
...e the nuts-and-bolts implementation:
import math
def cosine_similarity(v1,v2):
"compute cosine similarity of v1 to v2: (v1 dot v2)/{||v1||*||v2||)"
sumxx, sumxy, sumyy = 0, 0, 0
for i in range(len(v1)):
x = v1[i]; y = v2[i]
sumxx += x*x
sumyy += y*y
sumxy...
分布式系统的事务处理 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...个Master都提供read-write服务。这个模型是Master-Slave的加强版，数据间同步一般是通过Master间的异步完成，所以是最终一致性。 Master-Master的好处是，一台Master挂了，别的Master可以正常做读写服务，他和Master-Slave一样，当数据没有被...
API Versioning for Rails Routes
...espace :api do
namespace :v1 do
resources :users
end
namespace :v2 do
resources :users
end
match 'v:api/*path', :to => redirect("/api/v2/%{path}")
match '*path', :to => redirect("/api/v2/%{path}")
end
If your mind is still intact after this point, let me explain.
First,...
Finding quaternion representing the rotation from one vector to another
...
Quaternion q;
vector a = crossproduct(v1, v2);
q.xyz = a;
q.w = sqrt((v1.Length ^ 2) * (v2.Length ^ 2)) + dotproduct(v1, v2);
Don't forget to normalize q.
Richard is right about there not being a unique rotation, but the above should give the "shortest arc," which...
ReSharper Abbreviations List: Where can I modify it?
...
Just an update that in VS 2010 with ReSharper 6.1 the list of abbreviations now appears under ReSharper/Options/Code Editing/C#/C# Naming Style/Advanced Settings - at the bottom of the panel is a text area with a space-separated list of uppercase abbreviations. This took...
For each row return the column name of the largest value
...make examples using sample reproducible):
DF <- data.frame(V1=c(2,8,1),V2=c(7,3,5),V3=c(9,6,4))
colnames(DF)[apply(DF,1,which.max)]
[1] "V3" "V1" "V2"
A faster solution than using apply might be max.col:
colnames(DF)[max.col(DF,ties.method="first")]
#[1] "V3" "V1" "V2"
...where ties.method...
How can I list all tags in my Git repository by the date they were created?
...ioned by DarVar below)
As an example, in the git/git repo it will list the v2.10.0 tag last:
v2.9.1
v2.9.2
v2.9.3
v2.10.0-rc0
v2.10.0-rc1
v2.10.0-rc2
v2.10.0
The default order would not (git tag):
v2.1.2
v2.1.3
v2.1.4
v2.10.0
v2.10.0-rc0
v2.10.0-rc1
v2.10.0-rc2
v2.2.0
...