r - Assign values to an "offset" diagonal in a matrix -

-

if have matrix x of arbitrary dimensions, example: 

     [,1] [,2] [,3] [,4] [,5] [1,]    0    0    0    0    0 [2,]    0    0    0    0    0 [3,]    0    0    0    0    0 [4,]    0    0    0    0    0 [5,]    0    0    0    0    0

and want change 0s 1s starting column , moving 1 down , 1 right until end last column. if start column [,3] change result in

     [,1] [,2] [,3] [,4] [,5] [1,]    0    0    1    0    0 [2,]    0    0    0    1    0 [3,]    0    0    0    0    1 [4,]    0    0    0    0    0 [5,]    0    0    0    0    0

i thought maybe x[,3:ncol(x)][1:ncol(x)] <- 1 gave me 

     [,1] [,2] [,3] [,4] [,5] [1,]    0    0    1    0    0 [2,]    0    0    1    0    0 [3,]    0    0    1    0    0 [4,]    0    0    1    0    0 [5,]    0    0    1    0    0

we use row/column indexing. suppose if arbitrary column start 'n', create sequence column last column ('n1'), cbind sequence of 'n1', use subsetting 'x' , replace values 1.

 n <- 3  n1 <- n:ncol(x)  x[cbind(seq(n1), n1)] <- 1  x  #     [,1] [,2] [,3] [,4] [,5]  #[1,]    0    0    1    0    0  #[2,]    0    0    0    1    0  #[3,]    0    0    0    0    1  #[4,]    0    0    0    0    0  #[5,]    0    0    0    0    0

or option is

 x[seq(n1), n1] <- diag(ncol(x)-n+1)

or using sparsematrix

 library(matrix)  n <- 3  rn <- 5  cn <- 5  n1 <- n:cn  s1 <- sparsematrix(seq_along(n1), n1, x=1)  as.matrix(rbind(s1,matrix(0, nrow=rn-nrow(s1), ncol=ncol(s1))))

update

on bigger dataset

m1 <- matrix(0, nrow=1e6, ncol=100) system.time({   n <- 3   n1 <- n:ncol(m1)   m1[cbind(seq(n1), n1)] <- 1  }) #  user  system elapsed  # 0.117   0.096   0.212  which(m1==1, arr.ind=true)[,2] #[1]   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21 #[20]  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40 #[39]  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55  56  57  58  59 #[58]  60  61  62  63  64  65  66  67  68  69  70  71  72  73  74  75  76  77  78 #[77]  79  80  81  82  83  84  85  86  87  88  89  90  91  92  93  94  95  96  97 #[96]  98  99 100

data

 x <- matrix(0, 5, 5)

Comments

Post a Comment

Popular posts from this blog

qt - Using float or double for own QML classes -

-
i've created components , helper methods using c++ , qt used in qml gui. of methods calculate gui elements (size, transformations, scene graph items creation). target arm 32 bit using opengl / eglfs render output. opengl using float , qml using real (defined double ). what should use in c++ do not lose precision? if use qreal ( double ) shouldn't lose precision. if git grep float in qtbase.git , can find out bit more: dist/changes-5.2.0-**************************************************************************** dist/changes-5.2.0-* important behavior changes * dist/changes-5.2.0-**************************************************************************** dist/changes-5.2.0- dist/changes-5.2.0- - qt compiled qreal typedef'ed double on dist/changes-5.2.0: platforms. qreal float on arm chipsets before. guarantees more dist/changes-5.2.0- consistent behavior between platforms qt supports, binary dist/chan...
Read more

Create Outlook appointment via C# .Net -

-
i need create outlook appointment using microsoft.office.interop.outlook , while can work locally on own workstation , works if run web application via server's browser, not work when connect server externally. hence, think might permission issue. i changed application pool identity " localsystem " don't access denied error. unfortunately, doesn't work. the app behaves if appointment created, appointment doesn't appear in outlook. here include file on top of aspx.cs page using outlook = microsoft.office.interop.outlook; here code using pop appointment. outlook.application apptapp = new outlook.application(); outlook.appointmentitem appt = apptapp.createitem(outlook.olitemtype.olappointmentitem) outlook.appointmentitem; appt.subject = txtfirstname.text + " " + txtlastname.text; appt.body = txtcomment.text; appt.alldayevent = false; appt.start = datetime.parse(txtreminderdate.text + " 8:00 am"); appt.end = datetime.p...
Read more

ios - Swift Array Resetting Itself -

-
i have 2 arrays: pointhistory , datehistory . have nstimer , , when timer runs out, action called. in action appending int pointhistory , , current date string datehistory . here timer action: func timeraction() { let steppervalue = int(stepper.value) employee.numberofpoints = steppervalue networking.saveemployee(employee, completion: { (error) -> void in if error != nil { let alert = uialertcontroller(title: "error", message: "there error updating \(self.employee.name)'s points", preferredstyle: .alert) let alertaction = uialertaction(title: "ok", style: .cancel, handler: nil) alert.addaction(alertaction) self.presentviewcontroller(alert, animated: true, completion: nil) } }) var dateformatter = nsdateformatter() dateformatter.dateformat = "mm-dd-yyyy" dateformatter.timezone = nstimezone.localtimezone() var date = nsdate() var ...
Read more