[R] EXAMPLE OF HOW TO USE R FOR EXPONENTIAL DISTRIBUTION & EXPONENTIAL REGRESSION

[Sarah Goslee]

Hi,

Please also include R-help in your replies - I can't provide
one-on-one tutorials.

Without knowing where you got your sample code, it's hard to help. But
what are you trying to do?

It doesn't have to be that complicated:

x <- 1:10
y <- c(0.00, 0.00,0.0033,0.0009,0.0025,0.0653,0.1142,0.2872,0,1 )
plot(x, y, pch=20)

# basic straight line of fit
fit <- glm(y~x)

abline(fit, col="blue", lwd=2)
exp.lm <- lm(y ~ exp(x))
lines(1:10, predict(exp.lm, newdata=data.frame(x=1:10)))


On Tue, Nov 27, 2018 at 9:34 AM Tolulope Adeagbo
<tolulopeadeagbo using gmail.com> wrote:
>
> Hello,
>
> So I found this example online but there seems to be an issue with the "Start" points. the result is giving somewhat a straight line
>
> # get underlying plot
> x <- 1:10
> y <- c(0.00, 0.00,0.0033,0.0009,0.0025,0.0653,0.1142,0.2872,0,1 )
> plot(x, y, pch=20)
>
> # basic straight line of fit
> fit <- glm(y~x)
> co <- coef(fit)
> abline(fit, col="blue", lwd=2)
>
> # exponential
> f <- function(x,a,b) {a * exp(b * x)}
> fit <- nls(y ~ f(x,a,b), start = c(a=1 , b=c(0,1)))
> co <- coef(fit)
> curve(f(x, a=co[1], b=co[2]), add = TRUE, col="green", lwd=2)
>
>
> # exponential
> f <- function(x,a,b) {a * exp(b * x)}
> fit <- nls(y ~ f(x,a,b), start = c(a=1, b=1))
> co <- coef(fit)
> curve(f(x, a=co[1], b=co[2]), add = TRUE, col="green", lwd=2)
> # logarithmic
> f <- function(x,a,b) {a * log(x) + b}
> fit <- nls(y ~ f(x,a,b), start = c(a=1, b=1))
> co <- coef(fit)
> curve(f(x, a=co[1], b=co[2]), add = TRUE, col="orange", lwd=2)
>
> # polynomial
> f <- function(x,a,b,d) {(a*x^2) + (b*x) + d}
> fit <- nls(y ~ f(x,a,b,d), start = c(a=1, b=1, d=1))
> co <- coef(fit)
> curve(f(x, a=co[1], b=co[2], d=co[3]), add = TRUE, col="pink", lwd=2)
>
> On Tue, Nov 27, 2018 at 12:28 PM Sarah Goslee <sarah.goslee using gmail.com> wrote:
>>
>> Hi,
>>
>> Using rseek.org to search for exponential regression turns up lots of information, as does using Google.
>>
>> Which tutorials have you worked thru already, and what else are you looking for?
>>
>> Sarah
>>
>> On Tue, Nov 27, 2018 at 5:44 AM Tolulope Adeagbo <tolulopeadeagbo using gmail.com> wrote:
>>>
>>> Good day,
>>> Please i nee useful materials to understand how to use R for exponential
>>> regression.
>>> Many thanks.
>>


-- 
Sarah Goslee (she/her)
http://www.numberwright.com