average

Ruby on Rails field average?

由 假如想象 提交于 2019-12-09 04:24:48
问题 Is there an easy way to obtain the average of an attribute in a collection? For instance, each user has a score. Given a collection of user(s) (@users), how can you get the average score for the group? Is there anything like @users.average(:score)? I think I came across something like this for database fields, but I need it to work for a collection... 回答1: For your question, one could actually do: @users.collect(&:score).sum.to_f/@users.length if @users.length > 0 Earlier I thought, @users

django aggregation to lower resolution using grouping by a date range

由 孤人 提交于 2019-12-09 03:23:23
问题 horrible title, but let me explain: i've got this django model containing a timestamp (date) and the attribute to log - f.e. the number of users consuming some ressource - (value). class Viewers(models.Model): date = models.DateTimeField() value = models.IntegerField() for each 10seconds the table contains the number of users. something like this: | date | value | |------|-------| | t1 | 15 | | t2 | 18 | | t3 | 27 | | t4 | 25 | | .. | .. | | t30 | 38 | | t31 | 36 | | .. | .. | now i want to

get average column A based on a range of values in column B

由 孤者浪人 提交于 2019-12-08 21:34:43
问题 My dataframe has several columns as follows: df1 <- data.frame(A = c(1,2,4), B=c(1,3,1), C=c(1,1,3)) I have two conditions to get average values for column A. Condition 1: I want to get average of column A when B is 1, i.e. only row1 and row2 will be averaged. Condition 2: I want to get average of column B when column A's values are larger than 1 but smaller than 3, i.e. only row 2 will be considered. I know I can use filter to cut the dataframe to have column B = 1 only. However, I am unsure

Is there a fast way to the average colors from several framebuffers in WebGL / Javascript?

由 独自空忆成欢 提交于 2019-12-08 18:17:29
I am very new to the WebGL subject. What I want to do is to calculate the average color of 6 different framebuffers like the ones below in the picture. Now I am wondering what the best way to go about it would be? I tried to do gl.readPixels(0, 0, 256, 256, gl.RGBA, gl.UNSIGNED_BYTE, pixelValues); but that seems to be very slow... Is there a way that this can happen on the graphics card? this is how the FBO is set up - I have this from a tutorial: ... You have two options Write a fragment shader that runs once per row (per texture) by rendering a quad (1 x textureheight) and runs through all

compute Average in Bash [closed]

由 点点圈 提交于 2019-12-08 15:31:57
问题 Closed . This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed 4 years ago . Problem Statement Given N integers, compute their average, correct to three decimal places. Input Format The first line contains an integer N. This is followed by N integers, each on a new line. Output Format Display the average of the N integers, rounded off to three decimal places. Input

conditionally average excel data columns

由 痴心易碎 提交于 2019-12-08 13:31:17
问题 I have a health project spreadsheet that has a column of a symptoms and drugs a patient is taking. These are actually columns but I don't know how to write a column in stack overflow. symptom drug1 drug2 7 150 0 6 150 0 7 150 0 6 150 0 2 75 25 3 75 25 2 75 25 3 75 25 I need help writing a formula that will average all the days with a symptom level 6 and above vs all the days with a symptom level of 3 and below. Then apply it to the drug column days. For instance in the case above it looks

MATLAB Cell Array - Average two values if another column matches

由 妖精的绣舞 提交于 2019-12-08 11:00:18
问题 I have a cell array in which some of the entries have two data points. I want to average the two data points if the data were collected on the same day. The first column of cell array 'site' is the date. The fourth column is the data concentration. I want to average the fourth column if the data comes from the same day. For example, if my cell array looks like this: 01/01/2011 36-061-0069 1 10.4 01/01/2011 36-061-0069 2 10.1 01/04/2011 36-061-0069 1 7.9 01/05/2011 36-061-0069 1 13 I want to

Array to string conversion error in Codeigniter

由 ☆樱花仙子☆ 提交于 2019-12-08 09:56:54
问题 I'm trying to display an average result from the database to the view but I keep getting this error: A PHP Error was encountered Severity: Notice Message: Array to string conversion Filename: views/resultview.php Line Number: 38 Here is the code from the Controller: $average['avg'] = $this->quiz->getAverage($quizid); $this->load->view('resultview',array('quiz' => $quiz, 'score' => $score, 'average_score' => $average)); The function from the model is the following: function getAverage($quiz) {

Calculate average of 5 numbers using 2 functions and onchange event handlers

由 依然范特西╮ 提交于 2019-12-08 08:17:08
问题 What it is supposed to do is add up each of the numbers put in the text boxes then calculate the average by dividing it by 5. I have to use onchange event handlers and 2 functions and return the result to the calcAvg function.To each text box add an onchange event handler that calls a function named calcavg() and passes the function the value of that text box by referencing its document object. In the performCalc() function calculate the average of the five numbers then return the result to

Average Time to Reply to Message

由 有些话、适合烂在心里 提交于 2019-12-08 08:12:30
问题 Is it possible to calculate the average time to reply to a message just with the following columns: id | ref | client | admin | date | message id is the unique message number ref is the message reference number, which is not unique (searching for ref, ordering by date will show a conversation) client is ID of client, if it is a client message, else 0 if not a client admin is ID of admin, if it is an admin message, else 0 if not a client date is set up using datetime being the time of the
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