splice

perl discard first array element in map operation

流过昼夜 提交于 2019-12-11 02:24:00
问题 I'm starting to harness the power of perl map, and have run into a question that I couldn't find an answer to. Basically I am parsing the return of a unix command which has a header line that I don't need, and then 2 lines of information per item. Currently, I am doing this: (undef, @ret) = map { [split /\n/] } split(/(?:Host: )/, `cat /proc/scsi/scsi`); Which works fine to skip the header and give me one array element per "useful" line of text. However, I want to build a hash instead, which

Splice jQuery array of elements

青春壹個敷衍的年華 提交于 2019-12-11 01:19:58
问题 I'm trying to remove elements from a jQuery object using splice() . But, what ends up happening is every other item is removed. I'm assuming this is due to a re-index of using splice. I was to fade in each <li> so I need to start at the top. Is there a way to accomplish this, or perhaps a better way than what I'm doing here? <ul> <li class="module">item 1</li> <li class="module">item 1</li> <li class="module">item 1</li> <li class="module">item 1</li> <li class="module">item 1</li> <li class=

ImagMagick: How to add a gradient splice to an image using one convert command?

浪尽此生 提交于 2019-12-10 11:39:58
问题 Is it possible to add a gradient splice to the bottom of an image? It seems that gradient option requires -size, which I cannot provide because size of the image may varry. It's possible with convert and compose but I want to use only one command. Something like this (note that this is invalid currently): convert -fill gradient:black-white -gravity south splice 0x20 image1.jpg image2.jpg 回答1: My suggestion to you is to use -append instead of -splice . The image size may vary, but you can

How does the splice function work here?

大城市里の小女人 提交于 2019-12-10 10:56:03
问题 Please help me out to understand this example. function fun(a){ this.length = 1; this.splice = [].splice; this[0] = a; return this; }; Now, when I execute this function the result is an array. f = new fun('hi');// result will be : ["hi"] Why is that? If I remove this.length=1 OR this.splice = [].splice , the result will be different. f = new fun('hi'); // result will be : fun {0: "a", splice: function} Why is that? I also see this technique used in jQuery. Please describe to me how this is

How can I use Linux's splice() function to copy a file to another file?

a 夏天 提交于 2019-12-10 03:47:06
问题 here's another question about splice(). I'm hoping to use it to copy files, and am trying to use two splice calls joined by a pipe like the example on splice's Wikipedia page. I wrote a simple test case which only tries to read the first 32K bytes from one file and write them to another: #define _GNU_SOURCE #include <fcntl.h> #include <stdio.h> #include <unistd.h> #include <errno.h> #include <string.h> int main(int argc, char **argv) { int pipefd[2]; int result; FILE *in_file; FILE *out_file;

PERL删除数组元素的多种方法

坚强是说给别人听的谎言 提交于 2019-12-09 17:32:25
比如说: @array = ('ray', 'loca', 'simon', 'ray'); 这里,我们想删除‘ray’这个元素。 列出几种方法: 1. 用grep函数。 函数名 grep 调用语法 @foundlist = grep (pattern, @searchlist); 解说 与同名的UNIX查找工具类似,grep函数在列表中抽取与指定模式匹配的元素,参数pattern为欲查找的模式,返回值是匹配元素的列表。 例子 @list = ("This", "is", "a", "test"); @foundlist = grep(/^[tT]/, @list); 结果 @foundlist = ("This", "test"); 2. 用map函数 函数名 map 调用语法 @resultlist = map (expr, @list); 解说 此函数在Perl5中定义,可以把列表中的各个元素作为表达式expr的操作数进行运算,其本身不改变,结果作为返回值。在表达式expr中,系统变量$_代表各个元素。 例子 1、 @list = (100, 200, 300); @results = map ($_+1, @list); 2、@results = map (&mysub($_), @list); 结果 1、(101, 201, 301) 2、无 3.

在JavaScript中删除数组元素-Delete与Splice

…衆ロ難τιáo~ 提交于 2019-12-09 16:48:06
在数组元素上使用 delete 运算符 与使用 Array.splice 方法有 什么 Array.splice ? 例如: myArray = ['a', 'b', 'c', 'd']; delete myArray[1]; // or myArray.splice (1, 1); 如果可以像删除对象一样删除数组元素,为什么还要使用splice方法? #1楼 在尝试了解如何从数组中删除元素的每次出现时,我偶然发现了这个问题。 这里有一个比较 的 splice 和 delete 去除每一个 'c' 从 items 阵列。 var items = ['a', 'b', 'c', 'd', 'a', 'b', 'c', 'd']; while (items.indexOf('c') !== -1) { items.splice(items.indexOf('c'), 1); } console.log(items); // ["a", "b", "d", "a", "b", "d"] items = ['a', 'b', 'c', 'd', 'a', 'b', 'c', 'd']; while (items.indexOf('c') !== -1) { delete items[items.indexOf('c')]; } console.log(items); // ["a", "b

1D -> 2D Array W/Normal Curve Sub-Array Lengths

天涯浪子 提交于 2019-12-07 23:43:15
问题 I am trying to break a 1D array into a 2D array where the sub-arrays are of varying lengths. This variance should follow the gaussian curve [or a mound shape]. So, say the 2D array variable we make is named gaussianCurve. The array within gaussianCurve[0] & gaussianCurve[n] would be of length 1, and gaussianCurve[n/2] would be a maximum provided by a parameter "maxArrayLength". This forces the number of gaussianCurve indexes to become variable. Say I have the following psuedo-code: function

Question about epoll and splice

不想你离开。 提交于 2019-12-07 18:15:35
问题 My application is going to send huge amount of data over network, so I decided (because I'm using Linux) to use epoll and splice. Here's how I see it (pseudocode): epoll_ctl (file_fd, EPOLL_CTL_ADD); // waiting for EPOLLIN event while(1) { epoll_wait (tmp_structure); if (tmp_structure->fd == file_descriptor) { epoll_ctl (file_fd, EPOLL_CTL_DEL); epoll_ctl (tcp_socket_fd, EPOLL_CTL_ADD); // wait for EPOLLOUT event } if (tmp_structure->fd == tcp_socket_descriptor) { splice (file_fd, tcp_socket

Linux splice() returning EINVAL (“Invalid argument”)

江枫思渺然 提交于 2019-12-07 10:54:48
问题 I'm trying to experiment with using splice (man 2 splice) to copy data from a UDP socket directly to a file. Unfortunately the first call to splice() returns EINVAL. The man page states: EINVAL Target file system doesn't support splicing; target file is opened in append mode; neither of the descriptors refers to a pipe; or offset given for nonseekable device. However, I believe none of those conditions apply. I'm using Fedora 15 (kernel 2.6.40-4) so I believe splice() is supported on all