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Pandas: drop a level from a multi-level column index?

... 321 You can use MultiIndex.droplevel: >>> cols = pd.MultiIndex.from_tuples([("a", "b"), ("...
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Print all but the first three columns

... 19 Answers 19 Active ...
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How to print last two columns using awk

... 194 You can make use of variable NF which is set to the total number of fields in the input recor...
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How to sort a list/tuple of lists/tuples by the element at a given index?

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Generate random number between two numbers in JavaScript

Is there a way to generate a random number in a specified range (e.g. from 1 to 6: 1, 2, 3, 4, 5, or 6) in JavaScript? 23 A...
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Find indices of elements equal to zero in a NumPy array

... numpy.where() is my favorite. >>> x = numpy.array([1,0,2,0,3,0,4,5,6,7,8]) >>> numpy.where(x == 0)[0] array([1, 3, 5]) share | improve this answer | ...
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What is Weak Head Normal Form?

... These expressions are all in normal form: 42 (2, "hello") \x -> (x + 1) These expressions are 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) ...
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How do I find a “gap” in running counter with SQL?

...gap" in a counter column in an SQL table. For example, if there are values 1,2,4 and 5 I'd like to find out 3. 20 Answers ...
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Can dplyr package be used for conditional mutating?

... Use ifelse df %>% mutate(g = ifelse(a == 2 | a == 5 | a == 7 | (a == 1 & b == 4), 2, ifelse(a == 0 | a == 1 | a == 4 | a == 3 | c == 4, 3, NA))) Added - if_else: Note that in dplyr 0.5 there is an if_else function defined so an alternative would be to replace ifelse with i...
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C++常用排序算法汇总 - C/C++ - 清泛网 - 专注C/C++及内核技术

...堆排序(HeapSort),插入排序(InsertSort),希尔排序(ShellSort) 1、选择排序(SelectSort) /************************************ * 简单选择排序 * 稳定排序,O{n^2} ~ O{n^2} * 从首位开始,循环一次找出一个比首位小的值,交换 * * https://www.tsi...