r - Efficiently inserting default missing rows in a data.table -


suppose i've got following data.table :

dt <- data.table(id=c(1,1,1,1,1,1,2,2,2,2),            wday=c("mon","tue","wed","thu","fri","sat","mon","tue","thu","fri"),            val=c(2,3,5,8,6,2,3,4,2,6))      id wday val  1:  1  mon   2  2:  1  tue   3  3:  1  wed   5  4:  1  thu   8  5:  1  fri   6  6:  1  sat   2  7:  2  mon   3  8:  2  tue   4  9:  2  thu   2 10:  2  fri   6

this result of aggregation of data.table. represents count (val) of variable depending on week day (wday) different individuals (id). problem is, during operations i've lost week days count 0.

so question : how update data.table object efficiently inserting, each id, many rows there missing week days val=0 ?

the result following :

    id wday val  1:  1  mon   2  2:  1  tue   3  3:  1  wed   5  4:  1  thu   8  5:  1  fri   6  6:  1  sat   2  7:  1  sun   0  8:  2  mon   3  9:  2  tue   4 10:  2  wed   0 11:  2  thu   2 12:  2  fri   6 13:  2  sat   0 14:  2  sun   0

thanks lot help.

one straightforward way think of right use expand.grid combinations , use subset allow.cartesian = true:

setkey(dt, "id", "wday") vals <- c("mon", "tue", "wed", "thu", "fri", "sat", "sun") idx <- expand.grid(vals, unique(dt$id))[, 2:1] dt[j(idx), allow.cartesian=true]  #     id wday val #  1:  1  mon   2 #  2:  1  tue   3 #  3:  1  wed   5 #  4:  1  thu   8 #  5:  1  fri   6 #  6:  1  sat   2 #  7:  1  sun  na #  8:  2  mon   3 #  9:  2  tue   4 # 10:  2  wed  na # 11:  2  thu   2 # 12:  2  fri   6 # 13:  2  sat  na # 14:  2  sun  na

alternatively, possible directly build idx data table cj :

dt[cj(unique(dt$id),vals), allow.cartesian=true]

Comments

Post a Comment

Popular posts from this blog

php - cannot display multiple markers in google maps v3 from traceroute result -

i'm newbie in php mysql , google maps v3. have problems in google maps v3. made traceroute web based , map traceroute's result in google maps v3 final project of college education. have try many tutorials didn't work. have tried tutorials in forum nothing worked. problem cannot display multiple markers got location data database. maybe because i'm newbie , not know how do. confuse looping show markers. here code <?php error_reporting(e_all ^ (e_notice)); ini_set('max_execution_time', 360); $enable_log_user = false; global $ip, $host_name, $host_ip; $host = @$_post['host']; $trace = @$_post['trace']; $self = $_server['php_self']; include("phpsqlajax_dbinfo.php"); $connection = mysql_connect ('127.0.0.1', $username, $password); if (!$connection) { die('not connected : ' . mysql_error());} $db_selected = mysql_select_db($database, $connection); if (!$db_selected) { die ('can\'t use db : ...
Read more

c# - DetailsView in ASP.Net - How to add another column on the side/add a control in each row? -

i have detailsview control on page used edit various fields of record, works in respect. i looking way add 1 column (and if works, why not more) right, absolutely read-only, show same fields of record comparison purposes. i aware there no obvious way such thing out of box detailsview . have looked other controls (transposed gridview , recommended formview , listview ), nothing satisfies. have special data binding setup using detailsview , can't out of without losing features. anyone on how "hack in" additional columns (for display only) on detailsview ? the solution have now, use second detailsview , visible set false in aspx. in code, make sure databind hidden detailsview hosts data third column first, initial detailsview named itemdetails . and in item created event, pass third column html rendering of hidden controls (in last code block) : protected void itemdetails_itemcreated(object sender, eventargs e) { if (dataite...
Read more

javascript - firefox memory leak -

i have following script (i use raphaeljs also) draws circle, waits 1 second, draws circle again, etc (you can copy paste - functional, need include raphael raphaeljs.com): <div id="holder"> </div> <script src="raphael.js" type="text/javascript"></script> <script> var paper = raphael(10, 50, 320, 200); var rad = math.pi / 180; var finangle = 0; function sector(cx, cy, r, startangle, endangle, params) { var x1 = cx + r * math.cos(-startangle * rad), x2 = cx + r * math.cos(-endangle * rad), y1 = cy + r * math.sin(-startangle * rad), y2 = cy + r * math.sin(-endangle * rad); return ["m", cx, cy, "l", x1, y1, "a", r, r, 0, +(endangle - startangle > 180), 0, x2, y2]; } var path = sector(100,100,50,0,180); var arc = paper.path(path); function draw() { path = sector(100,100,50,0,finangle); ...
Read more