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What does “@@ -1 +1 @@” mean in Git's diff output?
...to-file to-file-modification-time
The time stamp looks like 2002-02-21 23:30:39.942229878 -0800 to indicate the date, time with fractional seconds, and time zone. The fractional seconds are omitted on hosts that do not support fractional time stamps.
You can change the header's content wi...
How can I get the intersection, union, and subset of arrays in Ruby?
...
155
Utilizing the fact that you can do set operations on arrays by doing &(intersection), -(di...
Does the ternary operator exist in R?
... returns the latest evaluation, if-else is equivalent to ?:.
> a <- 1
> x <- if(a==1) 1 else 2
> x
[1] 1
> x <- if(a==2) 1 else 2
> x
[1] 2
The power of R is vectorization. The vectorization of the ternary operator is ifelse:
> a <- c(1, 2, 1)
> x <- ifelse(a=...
Calculate difference in keys contained in two Python dictionaries
...
21 Answers
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LINGO使用指南 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...，利用LINGO高效的求解器可快速求解并分析结果。
§1 LINGO快速入门
当你在windows下开始运行LINGO系统时，会得到类似下面的一个窗口：
外层是主框架窗口，包含了所有菜单命令和工具条，其它所有的窗口将被包含在主窗口...
What is the bower (and npm) version syntax?
...example: to indicate you'll take any subsequent patch-level changes on the 1.2.x tree, starting with 1.2.0, but less than 1.3.0, you could use:
"angular": "~1.2"
or:
"angular": "~1.2.0"
This also gets you the same results as using the .x syntax:
"angular": "1.2.x"
But, you can use the tilde...
What is the difference between Ruby 1.8 and Ruby 1.9
I'm not clear on the differences between the "current" version of Ruby (1.8) and the "new" version (1.9). Is there an "easy" or a "simple" explanation of the differences and why it is so different?
...
Operation on every pair of element in a list
... module. It does exactly what you describe.
import itertools
my_list = [1,2,3,4]
for pair in itertools.product(my_list, repeat=2):
foo(*pair)
This is equivalent to:
my_list = [1,2,3,4]
for x in my_list:
for y in my_list:
foo(x, y)
Edit: There are two very similar functions as...
What is the syntax to insert one list into another list in python?
...
Do you mean append?
>>> x = [1,2,3]
>>> y = [4,5,6]
>>> x.append(y)
>>> x
[1, 2, 3, [4, 5, 6]]
Or merge?
>>> x = [1,2,3]
>>> y = [4,5,6]
>>> x + y
[1, 2, 3, 4, 5, 6]
>>> x.extend(y)
>&g...
get list from pandas dataframe column
... cast it with list(x).
import pandas as pd
data_dict = {'one': pd.Series([1, 2, 3], index=['a', 'b', 'c']),
'two': pd.Series([1, 2, 3, 4], index=['a', 'b', 'c', 'd'])}
df = pd.DataFrame(data_dict)
print(f"DataFrame:\n{df}\n")
print(f"column types:\n{df.dtypes}")
col_one_list = df['o...