dataframe - subsetting a large txt file before reading it into the variable in R -

-

this question has answer here:

i have large txt file (approx 2 mil rows). first column date in format 01/01/2006. values separated ;

data <- read.table("largefile.txt", sep=";")  datatouse <- data[data$date >= 01/02/2007 && data$date <= 02/02/2007,]

example row:

16/12/2006;17:36:00;5.224;0.478;232.990;22.400;0.000;1.000;16.000

above code doesn't work, there way subset first , load data data variable ? since file large, , takes time load ?

for subset work, need quotes , 1 less ampersand.

datatouse <- data[data$date >= "01/02/2007" & data$date <= "02/02/2007", ]

you use subset() function.

subset(data, date >= "01/02/2007" & date <= "02/02/2007")

next, if date column should date class variable, can set class argument colclasses in read.table(). can set column classes way if choose, or 1 use. make sure dates in proper format before using colclasses dates class variables.

finally, subset data before read onto r, recommend using shell/unix commands in terminal or shell. functions such grep, awk, sed, etc easy , quick reduce data before sending r. on windows i'd recommend download cygwin (it's free , fast), , terminal in linux-based machines.


Comments

Post a Comment

Popular posts from this blog

database - VFP Grid + SQL server 2008 - grid not showing correctly -

-
i having problem, have grid called "gridbasica" , this: thisform.gridbase.recordsource = "sgviemp" sgviemp cursor made executing select sqlserver command sqlexec. when want modify registry, go form , the update there. so, when come form grid, grid isnt grid anymore, big white rectangle. reading around said: delete recordsource , asingt again. thisform.gridbase.recordsource = "" *--i sqlexe here thisform.gridbase.recordsource = "sgviemp" i , works, but, when click button modify again cursos updated modify form doesnt load fields did first time. could me out that? thanks in advance. --------------- edit ------------------ i have been doing recommended: lnselect = select(0) n = sqlexec(thisform.conexion,"select emp_ccodigo codigo, emp_cnombre 'nombre o razon social', emp_cnumrif 'r.i.f' sgviempr","sgviemp1") set echo on suspend select sgviemp zap in sgviemp *-- browse *--zaps correct
Read more

jquery - Set jPicker field to empty value -

-
im using jpicker color selector in form. have clear value set window/icon 'no color selected' state. i've tried following: $(':input[name="color"]').val(''); //access value directly. (does not affect jpicker) 2: $.jpicker.list[0].color.active.val('hex', '', this); //set color black , input value 000000, instead of empty string 3: $.jpicker.list[0].color.active.val(null, '', this); //does nothing none of 3 methods seems behave properly. in advance. this works me :) $.jpicker.list[0].color.active.val('v', null); here example: http://jsfiddle.net/3up7n/
Read more

.htaccess - htaccess convert request to clean url and add slash at the end of the url -

-
ok , searched more 4 days , more 20 posts here in stach or in websites without kind of success first here htaccess file rewriteengine on rewriterule ^([a-za-z0-9_]+)/?$ index.php?page=$1 [nc] rewriterule ^([a-za-z0-9_]+)\/([a-za-z0-9_]+)\/?$ index.php?page=$1&action=$2 [nc] i tried many codes 1 worked me can call request , works me www.example.com/pagename => www.example.com/index.php?page=pagename here questions , please provide me information "in detail" understand code well 1- how convert request automatically www.example.com/index.php?page=pagename www.example.com/pagename 2- if tried add slash @ end shows me page without images or styling mean www.example.com/pagename => works www.example.com/pagename/ => doesn't work that's :) for first part need 301 rule this: rewritecond %{the_request} /index\.php\?page=([^\s&]+) [nc] rewriterule ^ /%1? [r=301,l] for second part use absolute path in css, js, images files r
Read more