stack

How can I stack columns per x columns in R

由 会有一股神秘感。 提交于 2020-05-23 07:41:26
问题 I'm looking to transform a data frame of 660 columns into 3 columns just by stacking them on each other per 3 columns without manually re-arranging (since I have 660 columns). In a small scale example per 2 columns with just 4 columns, I want to go from A B C D 1 4 7 10 2 5 8 11 3 6 9 12 to A B 1 4 2 5 3 6 7 10 8 11 9 12 Thanks 回答1: reshape to the rescue: reshape(df, direction="long", varying=split(names(df), rep(seq_len(ncol(df)/2), 2))) # time A B id #1.1 1 1 4 1 #2.1 1 2 5 2 #3.1 1 3 6 3

How can I stack columns per x columns in R

由 空扰寡人 提交于 2020-05-23 07:40:06
问题 I'm looking to transform a data frame of 660 columns into 3 columns just by stacking them on each other per 3 columns without manually re-arranging (since I have 660 columns). In a small scale example per 2 columns with just 4 columns, I want to go from A B C D 1 4 7 10 2 5 8 11 3 6 9 12 to A B 1 4 2 5 3 6 7 10 8 11 9 12 Thanks 回答1: reshape to the rescue: reshape(df, direction="long", varying=split(names(df), rep(seq_len(ncol(df)/2), 2))) # time A B id #1.1 1 1 4 1 #2.1 1 2 5 2 #3.1 1 3 6 3

Why Does My Prefix Expression Evaluator Program Miscalculate Any Addition or Subtraction?

由 吃可爱长大的小学妹 提交于 2020-05-17 05:56:28
问题 I have a program that is meant to take in a Queue<String> that contains the elements of a prefix operation (i.e. an operation that is stated "+ 4 2" instead of "4 + 2", which is infix), then output the integer answer (just assume that a double is never needed, okay?). It works correctly for any multiplication or division operation, but fails in any addition or subtraction operation, and worse, in an inconsistent manner. For example, the output to "- 5 1" is 5, which would suggest it's adding

Monotonic stacks and queues. Definition and examples

由 孤街浪徒 提交于 2020-04-18 06:11:22
问题 What exactly is a monotonic stack? (and e.g. how is it different from a monotonic queue?) E.g. consider the following array of integers: [0, 2, 1, 3, 4] . If I process this array left to right inserting it into a monotonically decreasing stack, what am I supposed to see in the stack, and why? Here's an example for a monotonically decreasing stack in Python that apparently is used in many solutions that solve the odd-even jump problem: def make(A): result = [None] * N stack = [] # invariant:

How to push elements in a stack using C

由 送分小仙女□ 提交于 2020-03-26 03:02:32
问题 I tried to learn a stack in C. But unable to do the push operation as it shows some errors in it. There is no error message shown in the console. But when running the code, it shows a wrong top value when executing the peek method. #include<stdio.h> #include<stdlib.h> #define MAX 50 typedef enum{FALSE,TRUE} boolean; typedef struct stack{ int top; int a[MAX]; }stack; void CreateStack(stack s){ s.top = -1; } boolean isEmpty(stack s){ return (s.top == -1); } boolean isFull(stack s){ return(s.top

Trouble replicating a stack buffer overflow exploit

由 你说的曾经没有我的故事 提交于 2020-03-24 10:20:29
问题 I am having trouble replicating the stack buffer overflow example given by OWASP here. Here is my attempt: $ cat test.c #include <stdio.h> #include <string.h> void doit(void) { char buf[8]; gets(buf); printf("%s\n", buf); } int main(void) { printf("So... The End...\n"); doit(); printf("or... maybe not?\n"); return 0; } $ gcc test.c -o test -fno-stack-protection -ggdb $ objdump -d test # omitted irrelevant parts i think 000000000040054c <doit>: 40054c: 55 push %rbp 40054d: 48 89 e5 mov %rsp,

How to know how much stack function is consuming?

由 人盡茶涼 提交于 2020-03-16 07:24:31
问题 Recently, I came across this question in an interview: How can we determine how much storage on the stack a particular function is consuming? 回答1: The "stack" is famously an implementation detail of the platform that is not inspectable or in any way queryable from within the language itself. It is essentially impossible to guarantee within any part of a C or C++ program whether it will be possible to make another function call. The "stack size", or maybe better called "function call and local

How to know how much stack function is consuming?

由 ╄→гoц情女王★ 提交于 2020-03-16 07:24:04
问题 Recently, I came across this question in an interview: How can we determine how much storage on the stack a particular function is consuming? 回答1: The "stack" is famously an implementation detail of the platform that is not inspectable or in any way queryable from within the language itself. It is essentially impossible to guarantee within any part of a C or C++ program whether it will be possible to make another function call. The "stack size", or maybe better called "function call and local

Stack Overflow大揭密：哪一种程序员工资最高？

由 倾然丶 夕夏残阳落幕 提交于 2020-03-06 13:52:20
　　Stackoverflow在程序员之间可以說是无人不知无人不晓，甚至常有人开玩笑说：“如果stackoverflow倒闭了，全世界代码的产出率将下降一半以上”或许听起来有点夸张，但是不难想像这个网站在软件界中扮演的重要地位。 　　 你知道根据stackoverflow统计，最受欢迎的程序语言是那一种吗？快来一探究竟吧！ 　　「Stack Overflow开发者调查」是由全球著名IT科技网站Stack Overflow发起的，专门针对该站注册开发者用户的问卷调查活动。该调查已经持续了三年之久。去年的调查是近年来规模最大，问题最多，涵盖范围最广的一次。 　　 最受欢迎的程序语言–Js Js 　　 写哪一种语言的工程师，薪水最高？ Object-C 　　根据StackOverflow统计，最赚钱的工程师用的是开发IOS应用程序的御用语言“Object-C”，紧接其后的是Java家族的“Node.js” 　　 在家工作的工程师收入比每天到办公室报到的工程师多40% 　　看来越来越多的程序员可以体验到自由工作的乐趣，并且学会了合理的分配时间来享受生活和工作，这里也希望越来越多的开发者加入我们程序员客栈www.proginn.com成为一名freelancer。 　　 76%的工程师满意自己的工作 　　而76%满意自己工作的工程师中有将近一半是热爱自己的工作的，接受调查的工程师中

Excel: How to create a Gantt Chart in Excel

由 六眼飞鱼酱① 提交于 2020-03-06 04:10:40
问题 Given the following data set: Request starttime Duration (ms) 1 00.000 222 2 00.005 257 3 00.001 270 4 00.003 299 5 00.292 198 6 00.327 199 7 00.318 319 8 00.333 451 9 00.511 323 I need to draw an overlapping bar graph, something akin to this overlapping bar graph (from google): However, when I try to draw the bar chart in mac excel, excel overloads the y-axis with request count and start time, rather than making start time and duration as both applied to the x-axis. In short, the y-axis is
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