How to calculate conditional means from .txt files

Question

I'm fairly new to programming and am looking for some guidance. Any help is appreciated.

Here's what I'm trying to do: I have a large number of.txt files from a cognitive experiment (Flanker task, if curious) that I need to compute means for based on condition. The files have no headers and look like below:

XXXXX 1 1 675
XXYXX 0 1 844
YYYYY 1 1 599
YYXYY 0 1 902

I would like to compute means for miliseconds (rightmost column; c4) based on the experimental condition (0 or 1; c2). I would also need the file name of each.txt file (my participant ID) included in the output.

I'm most familiar with R but really just for data analysis. I also have a little experience with Python and Matlab if those (or something else) better suit my needs. Again, a point in any direction would be greatly appreciated.

Thanks

Answer 1

The Tidyverse collection of packages specially the dplyr and readr can easy do this task for you on a grammar likely SQL.

Something like

#loading packages
library(tidyverse)

#importing data
df <- read_delim("file.txt", delim="|", col_names=c("col1", "col2", "col3", "col4"))

#dealing with data
#only mean for col2 == 1
df %>%
filter(col2 == 1) %>%
summarize(mean_exp = mean(col4))

#mean considering grouping by col2
df %>%
group_by(col2) %>%
summarize(mean_exp = mean(col4))

I may suggest you search for cheatsheets available on the links above. They are very easy to understand and reproduce the code.

Answer 2

Here is how you could do it in R:

# mimick your text files

cat("XXXXX 1 1 675",file="XXXXX.txt",sep="\n")
cat("XXYXX 0 1 844",file="XXYXX.txt",sep="\n")
cat("YYYYY 1 1 599",file="YYYYY.txt",sep="\n")
cat("YYXYY 0 1 902",file="YYXYY.txt",sep="\n")


# create a list
my_list_txt <- list.files(pattern=".txt")

files_df <- lapply(my_list_txt, function(x) {read.table(file = x, header = F)})

# create a dataframe
df <- do.call("rbind", lapply(files_df, as.data.frame))

# do the group calculation
library(dplyr)
df %>% 
  group_by(V2) %>% 
  summarise(mean = mean(V4))

     V2  mean
  <int> <dbl>
1     0   873
2     1   637