Removing YAML from an RMD file through an R script


So you want to write a book from many RMD files using bookdown.  Here is an R script that strips the YAML lines of an Rmd file because bookdown does not accept files with its own YAML. A new file is created that has no YAML.  The program is written just for one Rmd file, and I will be writing an extension of it to do this for a whole directory including subdirectories.  I will soon write a script that will move the YAML absent RMD files and associated sub-directories to a new directory of its own.

# A program to remove YAML from an RMD file. 
# It can be modified to do this for all
# files in a directory and/or its subdirectories 
# Stay tuned for the update.

#Set the working directory
setwd("C:/Users/yoda/Rmd")

# filename of the rmd file whose YAML you want to take out
fileName <- "Chapter01.03RoundoffErrors/0103RoundOffErrorsYaml.rmd"

# Open the file to read
Input_File <- file(fileName,open="r")
linn <-readLines(Input_File)

# icapture is a vector which will check the two lines 
# that have --- in them.
icapture <- vector(,10)

# Just printing the lines in the rmd file, not needed.
#for (i in 1:length(linn)){
# print(linn[i])
#}

#The name of the file which will store YAML free RMD file.
YAML_Remove_File <- file("Chapter01.03RoundoffErrors/0103RoundOffErrorsYamlRemove.rmd",open="w")

j <- 0
#Capturing the two line numbers where --- exists
for (i in 1:length(linn)){
if(strtrim(linn[i],3) == "---"){
j <- j+1
icapture[j] <- i
}

# Write to the output file only if it has already captured two --- 
if ((j==2) & (i!=icapture[2])){
writeLines(linn[i],con2)
}
}

#close the input and output files
close(Input_File)
close(YAML_Remove_File)

____________________________

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Author: Autar Kaw

Autar Kaw (http://autarkaw.com) is a Professor of Mechanical Engineering at the University of South Florida. He has been at USF since 1987, the same year in which he received his Ph. D. in Engineering Mechanics from Clemson University. He is a recipient of the 2012 U.S. Professor of the Year Award. With major funding from NSF, he is the principal and managing contributor in developing the multiple award-winning online open courseware for an undergraduate course in Numerical Methods. The OpenCourseWare (nm.MathForCollege.com) annually receives 1,000,000+ page views, 1,000,000+ views of the YouTube audiovisual lectures, and 150,000+ page views at the NumericalMethodsGuy blog. His current research interests include engineering education research methods, adaptive learning, open courseware, massive open online courses, flipped classrooms, and learning strategies. He has written four textbooks and 80 refereed technical papers, and his opinion editorials have appeared in the St. Petersburg Times and Tampa Tribune.

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