index value
  1     1     1
  2     2     1
  3     3     1
  4     4     1
  5     5     1

index value
1     4     3
2     5     3
3     6     3
4     7     3
5     8     3

index value
1     1     1
2     2     1
3     3     1
4     4     2 (as (1+4)/2 = 2)
5     5     2 (as (1+4)/2 = 2)
6     6     3
7     7     3
8     8     3

# locate the files
files <- list.files(my.csv.dir)

# read the files into a list of data.frames
data.list <- lapply(files, read.csv)

# concatenate into one big data.frame
data.cat <- do.call(rbind, data.list)

# aggregate
data.agg <- aggregate(value ~ index, data.cat, mean)

files     <- list.files(my.csv.dir)
algo.name <- sub("-.*", "", files)
data.list <- lapply(files, read.csv)
data.list <- Map(transform, data.list, algorithm = algo.name)
data.cat  <- do.call(rbind, data.list)
data.agg  <- aggregate(value ~ algorithm + index, data.cat, mean)

##Wanted to share below rMarkdown code that I gained from stackoverflow to solve my problem of combining multiple files into one master to analyze
    ```{r echo = FALSE, warning = FALSE, message = FALSE}
    Below is modified code of Daniel Marcelino
##set directory where you have your raw .csv files stored
    setwd("~/Data/R/Inventory/data/OnHandInventory/datacsv")
##below code will go into your directory and read all .csv files and rbind (stack) them into one master file as long as the headers are the same, if different look into smartbind()

    path = "~/Data/R/Inventory/data/OnHandInventory/datacsv/"
    out.file <- ""
    file.names <- dir(path, pattern =".csv")
    for(i in 1:length(file.names)){ file <- read.csv(file.names[i], header=TRUE, stringsAsFactors=FALSE)
    out.file <- rbind(out.file, file)
    }
##below writes out master file to specified directory
    write.csv(out.file, file="~/Data/R/Inventory/data/OnHandInventory/data/OnHandInv.csv", row.names = FALSE)
##go to new folder where combined file is located
    setwd("~/Data/R/Inventory/data/OnHandInventory/data")
##now read in the .csv
    OnHandInv <- read.csv("OnHandInv.csv", dec= ".", stringsAsFactors = FALSE)
    ```