Berechnen Sie zusammenfassende Statistiken von verschiedenen Spalten aus separaten data.frames

Question

Ich bin neu in R. Ich habe ein Verzeichnis enthalten viele Dataframe-Dateien, die die gleiche Struktur (3 Spalten durch ",") wie folgt haben: Datum und timestamp, V2, V3

Ich soll Mittelwert, Median, SD, Varianz und Schiefe für beide Spalten V2 und V3 für alle Dateien berechnen und dann diese 10 Spalten in einer separaten Datei speichern. Jede Spalte (z. B. V2-Median) enthält Medianwerte aller V2-Spalten in allen Dateien. Ich brauche deine Hilfe dafür.

Dank

Answer 1

Eine weitere Methode:

#This library is needed to compute skewness 
library(e1071) 

#Set the directory where your files are present as home directory 
setwd("Directory where your files are present") 

#file names will be stored 
files <- list.files(path = ".",pattern = ".CSV$", ignore.case = TRUE) 
file<-NULL 
for (i in 1:length(files)){ 
current_file=read.table(files[i],header = TRUE,sep = ",") 
v2_mean=sapply(current_file[2], mean, na.rm = TRUE) 
v2_median=sapply(current_file[2], median, na.rm = TRUE) 
v2_SD=sapply(current_file[2], sd, na.rm = TRUE) 
v2_variance=sapply(current_file[2], var, na.rm = TRUE) 
v2_Skew=sapply(current_file[2], skewness, na.rm = TRUE) 

v3_mean=sapply(current_file[3], mean, na.rm = TRUE) 
v3_median=sapply(current_file[3], median, na.rm = TRUE) 
v3_SD=sapply(current_file[3], sd, na.rm = TRUE) 
v3_variance=sapply(current_file[3], var, na.rm = TRUE) 
v3_Skew=sapply(current_file[3], skewness, na.rm = TRUE) 
file<-rbind.data.frame(file,c(v2_mean,v2_median,v2_SD,v2_variance,v2_Skew,v3_mean,v3_median,v3_SD,v3_variance,v3_Skew)) 
} 
names(file)<-c("v2_mean","v2_median","v2_SD","v2_variance","v2_Skew","v3_mean","v3_median","v3_SD","v3_variance","v3_Skew") 

#Final file will be saved in the home directory 
write.csv(file, "file_stats.csv") 

Answer 2

Wenn ich Sie Fragen richtig zu verstehen, ist hier eine schnelle Lösung data.table verwenden.

# Load library 
    library(data.table) 
    library(moments) 
    library(readr) 



# Get a List of `.csv` files in your folder 
    filenames <- list.files("C:/your/folder", pattern="*.csv", full.names=TRUE) 


# Load and bind all data sets into one single data frame 
    df <- rbindlist(lapply(filenames,fread)) 


# run the summary statistics for V2 and V3 

output <- df[,.( V2_mean= mean(V2) 
       , V2_median= median(V2) 
       , V2_SD= sd(V2) 
       , V2_var= var(V2) 
       , V2_skw= skewness(V2) 
       , V3_mean= mean(V3) 
       , V3_median= median(V3) 
       , V3_SD= sd(V3) 
       , V3_var= var(V3) 
       , V3_skw= skewness(V3)) ] 


# save output in a different file 
    write_csv(output, "output.csv")