search for: hydrologists

OK, this should be trivial but I'm not finding it. I want to compress the test, if (i==7 | i==10 | i==30 | i==50) {} into something like if (i in c(7,10,30,50)) {} so I can build a "excludes" vector excludes <- c(7,10,30,50) and test if (i in excludes) {} However, I'm not finding a clue on how to accomplish this, if it can be done. Would someone with more R

Hi I am using the quantreg package for median regression for a large series of subsets of data. It works fabulously for all but one subset. When it reaches this subset, R takes the command and never responds. I end up having to kill R and restart it. It appears to be something with the particular data subset, but I can't pinpoint the problem. Here are some details Operating system:

Good morning and I appreciate the availability of a help-list. I am a professional hydrologist, but not a professional statistician. Yet I find myself using statistical tools at least part of the time. My discovery of the R-project through a friend has been most helpful. Here is my problem: I'm tasked with fitting a dataset comprising correlated discharges from adjacent watersheds to

I am trying to fit a nonlinear regression to infiltration data in order to determine saturated hydraulic conductivity and matric pressure. The original equation can be found in Bagarello et al. 2004 SSSAJ (green-ampt equation for falling head including gravity). I am also VERY new to R and to nonlinear regressions. I have searched the posts, but am still unable to determine why my data come up

Eric B's response provided just the kind of quick & simple solution I was hoping for (appears as the function com below). However, I once again failed to take advantage of the power of R and have reverted back to using a for loop for the next step of the processing. The example below (which requires the library EGRET for pulling an example dataset) works, but probably can be replaced

Hi Eric, the following works for me. HTH, Eric library(EGRET) StartDate <- "1990-10-01" EndDate <- "2017-09-30" siteNumber <- "10310000" QParameterCd <- "00060" Daily <- readNWISDaily(siteNumber, QParameterCd, StartDate, EndDate) # Define 'center of mass' function com <- function(x) { match(TRUE, cumsum(x/sum(x)) > 0.5) -

...ent, analysis, interpolation and plot of hydrological time series, mainly oriented to hydrological modelling tasks. So far, it only works with daily / monthly / seasonal / annual time series. The focus of this package has been put in providing a collection of functions useful for the daily work of hydrologists, and although an effort was made to optimise each function as much as possible, functionality has had priority over speed. ############ # hydroGOF # ############ 2) hydroGOF is a package for comparison of simulated and observed hydrological time series: http://cran.r-project.org/web/packages/hy...

...ent, analysis, interpolation and plot of hydrological time series, mainly oriented to hydrological modelling tasks. So far, it only works with daily / monthly / seasonal / annual time series. The focus of this package has been put in providing a collection of functions useful for the daily work of hydrologists, and although an effort was made to optimise each function as much as possible, functionality has had priority over speed. ############ # hydroGOF # ############ 2) hydroGOF is a package for comparison of simulated and observed hydrological time series: http://cran.r-project.org/web/packages/hy...

Hi,Has anybody worked with thornthwaite method to calculate the daily evapotranspiration ? I have used the following code to calculate monthly evaporation but what I need is daily evapotranspiration. Epot <- thornthwaite(Tave, lat, na.rm = FALSE) # Evaluates evapotranspiration for each month. Do you have any code which works for daily timestep ? Its more technical question, may be some

Hi… I want to use grImport to create a watermark on a plot() using the methods Paul Murrell describes here: http://cran.r-project.org/web/packages/grImport/vignettes/import.pdf (page 28). I can essentially reproduce this manually at the R prompt, and independently I can use grid.picture(…) successfully in a R script, but when I attempt to do do this in my script: • • •

...z data from Z to the bottom to find the storage. Plot the storage at each water surface to get an idea of the shape and then use lm(Elevation~f(Storage) where f(Storage) may be a cubic or quartic polynomial. Then double the Storage and calculate Elevation. This type of thing is done everyday by hydrologists. Good luck David K Stevens, PhD, PE, Professor Civil and Environmental Engineering Utah Water Research Laboratory Utah State University 8200 Old Main Hill Logan, UT 84322-8200 david.stevens at usu.edu (435) 797-3229 (office) On 4/9/2024 8:01 AM, peter dalgaard wrote: > So, you know how to get...

...the bottom to find the storage. Plot the storage at > each water surface to get an idea of the shape and then use > lm(Elevation~f(Storage) where f(Storage) may be a cubic or quartic > polynomial. Then double the Storage and calculate Elevation. This type > of thing is done everyday by hydrologists. > > Good luck > > David K Stevens, PhD, PE, Professor > Civil and Environmental Engineering > Utah Water Research Laboratory > Utah State University > 8200 Old Main Hill > Logan, UT 84322-8200 > david.stevens at usu.edu > (435) 797-3229 (office) > > On 4/9/20...

...\frac{k}{n}}{p(k) = k / n}. That is, linear interpolation of the empirical cdf.} \item{Type 5}{\eqn{p(k) = \frac{k - 0.5}{n}}{p(k) = (k - 0.5) / n}. That is a piecewise linear function where the knots are the values midway through the steps of the empirical cdf. This is popular amongst hydrologists.} \item{Type 6}{\eqn{p(k) = \frac{k}{n + 1}}{p(k) = k / (n + 1)}. Thus \eqn{p(k) = \mbox{E}[F(x_{k})]}{p(k) = E[F(x[k])]}. This is used by Minitab and by SPSS.} \item{Type 7}{\eqn{p(k) = \frac{k - 1}{n - 1}}{p(k) = (k - 1) / (n - 1)}. In this case, \eqn{p(k) = \mbox{mode}[F(x_{k})]}{p(k)...

Hi Eric, How about match( TRUE, cumsum(hyd/sum(hyd)) > .5 ) - 1 HTH, Eric On Sat, Dec 16, 2017 at 3:18 PM, Morway, Eric <emorway at usgs.gov> wrote: > The small bit of script below is an example of what I'm attempting to do - > find the day on which the 'center of mass' occurs. In case that is the > wrong term, I'd like to know the day that essentially cuts

The small bit of script below is an example of what I'm attempting to do - find the day on which the 'center of mass' occurs. In case that is the wrong term, I'd like to know the day that essentially cuts the area under the curve in to two equal parts: set.seed(4004) Date <- seq(as.Date('2000-09-01'), as.Date('2000-09-30'), by='day') hyd <-

...(in package reshape) and summary.formula (in package Hmisc). * Renext (1.0-0) IRSN http://crantastic.org/packages/Renext R package dedicated to some Extreme values problems and allowing the use of the so-called &quot;renewal method&quot; which is popular among french-speaking hydrologists. * rgp (0.1-0) Oliver Flasch http://crantastic.org/packages/rgp RGP is a simple modular Genetic Programming (GP) system build in pure R. In addition to general GP tasks, the system supports Symbolic Regression by GP through the familiar R model formula interface. GP individuals are re...