Displaying 20 results from an estimated 8000 matches similar to: "Open file for reading and writing with APPEND"
2011 Sep 12
1
Open a file to APPEND
Hi,
I want to store the output of my program to a file. However, With subsequent runs of my code, I'd like to append to the same log file.
Currently, I'm using:
outfile <- file("log.txt", open="w")
cat(results, file=outfile)
This works, but will overwrite the log file each time.
Is there a way to open a file and have R append to the end?
Thanks!
--
Noah
2012 May 18
2
Failure building any package
Hello,
I'm attempting to build a package using R 2.15.0 on OS X
I am getting a generic failure when performing a cran type check on the package. Even with a very simple test package, it still fails int he same place.
Example:
In R:
rm(list=ls())
foo <- function(x){print(x)}
package.skeleton(name="foo")
Then, at the command line:
R CMD build foo
R CMD check --as-cran
2011 Sep 02
2
Avoiding for Loop for moving average
Hello,
I need to calculate a moving average and an exponentially weighted moving average over a fairly large data set (500K rows).
Doing this in a for loop works nicely, but is slow.
ewma <- data$col[1]
N <- dim(data)[1]
for(i in 2:N){
data$ewma <- alpha * data$ewma[i-1] + (1-alpha) * data$value[i]
}
Since the moving average "accumulates" as we move through the data,
2012 Jun 11
3
Decision Trees or Markov Models for Cost Effectiveness
Hello,
I was just assigned to perform a cost effectiveness study in healthcare. We are studying the cost effectiveness of a proposed diagnostic vs. current screening procedures.
One of the team members suggest a commercial software package called "TreeAge Pro". Looking at the description, it appears to be a nice GUI to some very simple models that could be easily constructed in R.
2012 Oct 09
4
Convert COLON separated format
I have a bunch of data sets that were created for the libsvm tool. They are in "colon separated sparse format".
i.e.
1 5:1 27:3 345:10
Is a row with the label of "1" and only has values in columns 5, 27, and 345.
I want to read these into a data.frame in R.
Is there a simple way to do this?
--
Noah Silverman, M.S.
UCLA Department of Statistics
8117 Math Sciences
2012 May 18
4
Menus - best practices?
Hello,
I need to design a fairly simple front-end for someone to use an R script system that I've built. My thought was to just use the text based menus available in the base R package, perhaps in some kind of loop.
How have other people done this? Any "best practices" that you can recommend?
Thanks!
--
Noah Silverman
UCLA Department of Statistics
8117 Math Sciences Building
2012 Oct 14
4
Date Math
Hello,
I have a time series object (xts) that I iterate over in a loop. Works fine.
My challenge is that I want to be able to reference other entries in the series by math. i.e. For today's observation, what were the last 5 observations? If indexed numerically, it is trivial, but I can figure out how to do this with dates.
This is slightly more difficult as there may not be an
2012 May 29
2
Converting to XTS loses data.frame structure
Hello,
I noticed something odd when working with data frames and xts objects.
If I read in a CSV file, R creates a nice data.frame. This works well.
If I then convert to an XTS object, I see that all the values in the data are now quoted. My data is a mix of numeric and character. This is usually seen when converting a data.frame to a matrix, as R will treat all the data as the same class.
2011 Aug 23
2
dummy variables from factors
Hi,
Looking at a large data set with many factors.
I would like to expand each factor variable into multiple new variables for each level. (0,1) coding.
My first though was just to code a big nasty loop, to take each level and cbind a column onto my data set. But, that seems painful. There must be a better way.
Is there an "easy" way to do this in R?
(Note, I don't want to
2012 Feb 28
6
Cleaning up messy Excel data
Unfortunately, some data I need to work with was delivered in a rather messy Excel file. I want to import into R and clean up some things so that I can do my analysis. Pulling in a CSV from Excel is the easy part.
My current challenge is dealing with some text mixed in the values.
i.e. 118 5.7 <2.0 3.7
Since this column in Excel has a "<2.0" value, then R reads the
2011 Aug 20
1
Raw epoch time from XTS
Hi,
I have a very large data set stored as an xts object.
xts is very nice about showing row labels as "human readable" dates and times.
I want the actual epoch values that are stored internally. The only way I can find to access them is one-at-a-time using the internal function: xcoredata()
Calling this in an entire column, the "R" way doesn't work. It will only
2011 Jun 20
1
access objects by name
Hi,
I have several data structures (xts structures). I then have a list of the names of those objects.
I'd like to access the object by name.
For example:
foo1 <- as.xts(....)
foo2 <- as.xts(...)
foo3 <- as.xts(...)
structs <- c("foo1", "foo2", "foo3")
for (thisOne in structs){
print(thisOne$colA)
}
The above fails. Clearly I'm missing a
2011 Aug 23
1
Glmnet lambda value choice
Hi,
When using the glmnet() function of the package glmnet, A series of coefficients is returned for a list of descending lambda values.
I am unable to locate anything in the documentation that explains HOW this choice of lambda series is made. (There is documentation about how to choose my own, but I want to understand how the authors are doing it)
Any ideas?
--
Noah Silverman
UCLA
2011 Oct 16
1
Read wav file into R
Hi,
I'm interested in doing some sound analysis with R.
Does anyone have any experience/methods for reading in a wav file?
--
Noah Silverman
UCLA Department of Statistics
8208 Math Sciences Building
Los Angeles, CA 90095
[[alternative HTML version deleted]]
2012 Mar 17
1
plot only non-zero values
Hi,
i have some data in a matrix. It has zero values scattered throughout, at random.
I'd like to create a line plot, with a line for each row, that *excludes* the zero or NA values.
The data looks like this (toy example)
10 12 21 0 23 0 43 0 NA 41
0 0 0 34 35 0 35 0 44 0
NA NA NA 3 2 5 0 3 2
etc...
Suggestions on an easy way to do this?
Thanks!
--
Noah Silverman
UCLA Department of
2012 Apr 06
1
Converting data frame to its object results in matrix of strings
Hi,
I have a rather large data frame (500 x 5000) that I want to convert to a proper xts object.
I am able to properly generate an xts object with the correct time index. However, all of my numerical values are now strings.
b <- as.xts(a[,2:dim(a)[2]], order.by=as.POSIXct(strptime(paste(a$Date), '%m/%d/%Y')))
My guess is that somewhere in the large data frame there are a few
2013 Apr 16
2
Strange error with log-normal models
Hi,
I have some data, that when plotted looks very close to a log-normal distribution. My goal is to build a regression model to test how this variable responds to several independent variables.
To do this, I want to use the fitdistr tool from the MASS package to see how well my data fits the actual distribution, and also build a generalized linear model using the glm command.
The summary
2012 Nov 25
1
rjags and parallel chains
Hello,
I have a fairly complex hierarchical model that I using rjags to fit. Short test runs verify that it works and everything appears to be setup correctly.
Now that I want to collect a larger sample from the posterior (5,000 or more). This looks like it will take several days to run on my hardware (Intel core i7, 16GB RAM)
I read in the rjags documentation that there is an option for
2011 Dec 10
1
Difficult subset challenge
Hi,
I'm having difficulty coming up with a good way to subest some data to generate statistics.
My data frame has multiple observations by group.
Here is an overly-simplified toy example of the data
==========================
code v1 v2
G1 1.2 2.3
G1 0 2.4
G1 1.4 3.4
G2 2.9 2.3
G2 4.3 4.4
etc..
=========================
I want to normalize the data *by group* for certain variable.
2011 Aug 25
1
Optim function with multivariate inputs
Hi,
I have function that I want to optimize. Am playing with the optim() function in R
Two issues:
1) I can't seem to get it to work with a function that takes multiple inputs.
Dummy Example:
myFunc <- function(A,B,D,D){
# Do stuff
return E
}
> myFunc(1,2,3,4)
[1] 12
# works fine from command line
> optim( par=c(1,2,3,4), fn=myFunc)
Error in A+B : 'B' is missing