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SQL RANK() versus ROW_NUMBER()
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ROW_NUMBER : Returns a unique number for each row starting with 1. For rows that have duplicate values,numbers are arbitarily assigned.
Rank : Assigns a unique number for each row starting with 1,except for rows that have duplicate values,in which case the same ranking is assigned and a ...
What's the fastest way to merge/join data.frames in R?
...In particular it never looks for duplicate keys. (continued after code)
DF1 = data.frame(a = c(1, 1, 2, 2), b = 1:4)
DF2 = data.frame(b = c(1, 2, 3, 3, 4), c = letters[1:5])
merge(DF1, DF2)
b a c
1 1 1 a
2 2 1 b
3 3 2 c
4 3 2 d
5 4 2 e
DF1$c = DF2$c[match(DF1$b, DF2$b)]
DF1$c
[1] a b ...
Applying a function to every row of a table using dplyr?
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edited Aug 6 '19 at 3:20
answered Jul 14 '14 at 0:20
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What's the best way to get the last element of an array without deleting it?
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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...
Peak signal detection in realtime timeseries data
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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?
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How to strip HTML tags from a string in SQL Server?
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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...