dataset - Filtering data in R (complex) -


i have dataset 7 million records.

i need filter data show 9000 of these.

the first field dmg primary key , take format 1-apr-123456. there 12 occurrences of each dmg value.

another column o_y , takes value of 0 or 1. 0, 1 on 900 occasions.

i return rows same dmg value, @ least 1 of records has , o_y value of 1.

i recommend using data.table doing (fread in data.table quite handy in reading in large data set have enough ram).

i not sure following best way in data.table but, @ least, should started. hopefully, else come along , list idiomatic data.table way this. can think of right now:

assuming data.table called dt , has 2 columns dmg , o_y. use o_y index key dt , subset dt o_y == 1 (dt[.(1)] in data.table syntax). find corresponding dmg values. unique of these dmg values keys.with.ones. succinctly done follows:

setkey(dt, o_y) keys.with.ones <- unique(dt[.(1), dmg][["dmg"]])

next, need extract rows corresponding these values of dmg. need change key dt dmg , extract rows corresponding keys above:

setkey(dt, dmg) dt.filtered <- dt[.(keys.with.ones)]

and done. :)

please refer ?data.table figure out better method if possible , let know.


Comments

Post a Comment

Popular posts from this blog

jquery - How can I dynamically add a browser tab? -

since using iframes house external pages are, accounts "not preferred method" , disallowed sites (flickr, one), want dynamically generate browser tabs. e.g., when user submits form, want dynamically generate tab on browser in response submitted. e.g., might want add new tab url like: http://www.bigsurgarrapata.com/contact how in jquery? you want form target attribute action attribute. http://www.w3schools.com/tags/att_form_target.asp browsers have ultimate control on result of target attribute open new tab value of _blank. <form action="contact_submit.php" target="_blank" method="post">
Read more

node.js - Getting the socket id,user id pair of a logged in user(s) -

i have web application done using node js , in it,i have authentication system requires users log in before can access pages. have 2 pages,the homepage , updates page. from read docs,a new socket id issued when user opens tab in browser. me being admin,i know socket id of logged in user , more so,the socket id,logged in user id pair logged in users. what method can use socket id,logged in user id pair make sure broadcast realtime info users online?.
Read more

keyboard - C++ GetAsyncKeyState alternative -

i using windows.h library's getasynckeystate function define key pushed on keyboard . here program returns int value of pushed key example. #include <iostream> #include <windows.h> using namespace std; int main (){ char i; for(i=8;i<190;i++){ if(getasynckeystate(i)== -32767){ cout<<int (i)<<endl; } } return 0; } but trying make opengl simple game , function appeared slow . there function not need cycle 180 times , if statement . thanks you're trying make opengl game, you're going use glfw. if that's case can away using glfwgetkey() such: if (glfwgetkey(glfw_key_up) == glfw_press) {...} if (glfwgetkey(glfw_key_down) == glfw_press) {...} that method nicely explained in tutorial 6 opengl-tutorial.org . should start first tutorial of beginners tutorials , later intermediate tutorials . if you're going make win32 window can listen wm_keydown or wm_keyup messages , virtua
Read more