I am a chemist dealing with a significant amount of voltammetry data recently. Let me be very clear and give some research information. I run scans from a starting voltage to an ending voltage on solid state conductive films. These scans are saved as .txt files (name scheme: run#.txt) in a single folder. I am looking at how conductance changes as temperature changes. The LINEST line plotting current v. voltage at a given temperature gives me a line with slope = conductance. Once I have the conductances (slopes) for each scan, I plot conductance v. temperature to see the temperature dependent conductance characteristics. I had been doing this in Excel, but have found quicker ways to get the job done using R. I am brand new to R (Rstudio) and recognize that my coding is not the best. Without doubt, this process can be streamlined and sped up which would help immensely. This is how I am performing the process currently:
# Set working directory with folder containing all .txt files for inspection
# Add all .txt files to the global environment
allruns<-list.files(pattern=".txt")
for(i in 1:length(allruns))assign(allruns[i],read.table(allruns[i]))
Since the voltage column (a 1x1000 matrix) is the same for all runs and is in column V1 of each .txt file, I assign a x to be the voltage column from the first folder
x<-run1.txt$V1
All currents (these change as voltage changes) are found in the V2 column of all the .txt files, so I assign y# to each. These are entered one at a time..
y1<-run1.txt$V2
y2<-run2.txt$V2
y3<-run3.txt$V2
# ...
yn<-runn.txt$V2
So that I can get the eqn for each LINEST (one LINEST for each scan and plotted with abline later). Again entered one at a time:
run1<-lm(y1~x)
run2<-lm(y2~x)
run3<-lm(y3~x)
# ...
runn<-lm(yn~x)
To obtain a single graph with all LINEST (one for each scan ) on the same plot, without the data points showing up, I have been using this pattern of coding to first get all data points on a single plot in separate series:
plot(x,y1,col="transparent",main="LSV Solid Film", xlab = "potential(V)",ylab="current(A)", xlim=rev(range(x)),ylim=range(c(y3,yn)))
par(new=TRUE)
plot(x,y2,col="transparent",main="LSV Solid Film", xlab = "potential(V)",ylab="current(A)", xlim=rev(range(x)),ylim=range(c(y3,yn)))
par(new=TRUE)
plot(x,y3,col="transparent",main="LSV Solid Film", xlab = "potential(V)",ylab="current(A)", xlim=rev(range(x)),ylim=range(c(y1,yn)))
# ...
par(new=TRUE)
plot(x,yn,col="transparent",main="LSV Solid Film", xlab = "potential(V)",ylab="current(A)", xlim=rev(range(x)),ylim=range(c(y1,yn)))
#To obtain all LINEST lines (one for each scan, on the single graph):
abline(run1,col=””, lwd=1)
abline(run2,col=””,lwd=1)
abline(run3,col=””,lwd=1)
# ...
abline(runn,col=””,lwd=1)
# Then to get each LINEST equation:
summary(run1)
summary(run2)
summary(run3)
# ...
summary(runn)
Each time I use summary(), I copy the slope and paste it into an Excel sheet- along with corresponding scan temp which I have recorded separately. I then graph the conductance v temp points for the film as X-Y scatter with smooth lines to give the temperature dependent conductance curve. Giving me a single LINEST lines plot in R and the conductance v temp in Excel.
This technique is actually MUCH quicker than doing it all in Excel, but it can be done much quicker and efficiently!!! Also, if I need to change something, this entire process needs to be reexecuted with whatever change is necessary. This process takes me maybe 5 hours in Excel and 1.5 hours in R (maybe I am too slow). Nonetheless, any tips to help automate/streamline this further are greatly appreciated.