R help - Apr 2018 - Syntax for capturing and writing file names

Hi all,

I am looking for syntax to read a list of *txt files, (loop through?) 
each with a different data content but same fields, then run lines of 
code to produce summary stats (I have working code for this) and add the 
matching data file name when writing the results of a line of R code.?? 
Suggestions on any package vignettes that may be useful welcomed.

My manual code for this is below and need to understand how to have the 
"DataFile" name changed to match the name of each data file as it is 
read and processed.

*write.csv(BatStats,file="C:\\=Bat data working\\Acoustic 
Parameters\\DataFile_Stats.csv")*

-- 

Bruce W. Miller, PhD.
Neotropical bat risk assessments
Conservation Fellow - Wildlife Conservation Society

If we lose the bats, we may lose much of the tropical vegetation and the lungs
of the planet

Using acoustic sampling to identify and map species distributions for >25
years.

Providing free Interactive identification keys and call fact sheets for the
vocal signatures of New World Bats


	[[alternative HTML version deleted]]

Hello,

You can process several files at a time with repeated use of *appy 
functions. Something like the following (not tested).


# This first instruction may not be needed
old_dir <- setwd("path/to/txt/files")

# Get the filenames in a vector and read them in
txt_files <- list.files(pattern = ".*\\.txt")
txt_list <- lapply(txt_files, read.table, args)


In the above lapply command, args are the arguments to read.table. For 
instance, header = TRUE, stringsAsFactors = FALSE, etc.

Now put your summary stats code in a function and run it through the 
data.frames in the list. Then save the results as csv files.


stats_list <- lapply(txt_list, summary_stats_function)

csv_files <- sub("txt", "csv", txt_files)
lapply(seq_along(csv_files), function(i) write.csv(stats_list[[i]], 
csv_files[i]))

setwd(old_dir)    # reset, if needed


Hope this helps,

Rui Barradas



On 4/19/2018 12:45 PM, Neotropical bat risk assessments
wrote:
> Hi all,
> 
> I am looking for syntax to read a list of *txt files, (loop through?)
> each with a different data content but same fields, then run lines of
> code to produce summary stats (I have working code for this) and add the
> matching data file name when writing the results of a line of R code.
> Suggestions on any package vignettes that may be useful welcomed.
> 
> My manual code for this is below and need to understand how to have the
> "DataFile" name changed to match the name of each data file as it
is
> read and processed.
> 
> *write.csv(BatStats,file="C:\\=Bat data working\\Acoustic
> Parameters\\DataFile_Stats.csv")*
>