| Both sides previous revisionPrevious revisionNext revision | Previous revision |
| r:input_output [2017/09/27 23:52] – [Reading from CSV Files] hkimscil | r:input_output [2019/09/20 01:32] (current) – [Reading from CSV Files] hkimscil |
|---|
| > source("script.R") # Run the script, capturing its output | > source("script.R") # Run the script, capturing its output |
| > sink() # Resume writing output to console</code> | > sink() # Resume writing output to console</code> |
| | |
| | <code>cat(data, file="analysisReport.out") |
| | cat(results, file="analysisRepart.out", append=TRUE) |
| | cat(conclusion, file="analysisReport.out", append=TRUE)</code> |
| | |
| | Without "append=TRUE" option, the content will be **overwritten** with the succeeding content. The above method is tedious and error prone. The second line has a different filename. The below method (making connection to file with file function) is better. |
| |
| <code>con <- file("analysisReport.out", "w") | <code>con <- file("analysisReport.out", "w") |
| close(con)</code> | close(con)</code> |
| |
| | "file("filename.txt", "w")" opens "filename.txt and remains open until "close(opened_variable)" function. In this case, append=TRUE option is not necessary. |
| ====== Listing Files ====== | ====== Listing Files ====== |
| <code>list.files()</code> | <code>list.files()</code> |
| Yates Frank 1902 1994 | Yates Frank 1902 1994 |
| Smith Kirstine 1878 1939 | Smith Kirstine 1878 1939 |
| | |
| </code> | </code> |
| |
| <code>> records <- read.fwf("fixed-width.txt", widths=c(10,10,4,-1,4)) | <code>> records <- read.fwf("http://commres.net/wiki/_export/code/r/input_output?codeblock=11", widths=c(10,10,4,-1,4)) |
| </code> | </code> |
| |
| 5 Smith Kirstine 1878 1939 | 5 Smith Kirstine 1878 1939 |
| </code> | </code> |
| | Funky variable names (V1, V2, . . .). Use the below method with "col.names=c()" option. |
| |
| | <code>> records <- read.fwf("http://commres.net/wiki/_export/code/r/input_output?codeblock=11", widths=c(10,10,4,-1,4), |
| | + col.names=c("Last","First","Born","Died")) |
| | > records |
| | Last First Born Died |
| | 1 Fisher R.A. 1890 1962 |
| | 2 Pearson Karl 1857 1936 |
| | 3 Cox Gertrude 1900 1978 |
| | 4 Yates Frank 1902 1994 |
| | 5 Smith Kirstine 1878 1939 |
| | </code> |
| ====== Reading Tabular Data Files ====== | ====== Reading Tabular Data Files ====== |
| <code>> dfrm <- read.table("filename")</code> | <code>> dfrm <- read.table("filename")</code> |
| </code> | </code> |
| |
| <code>> tbl <- read.csv("filename")</code> | <code>> tbl <- read.csv("filename.csv") |
| | > tbl</code> |
| |
| <code>> tbl <- read.csv("filename", header=FALSE)</code> | <code>> tbl <- read.csv("filename.csv", header=FALSE) |
| | > tbl</code> |
| | |
| | <code>> tbl <- read.csv("filename.csv", header=FALSE, sep="\t") |
| | > tbl</code> |
| |
| <code>> str(tbl) | <code>> str(tbl) |
| > url <- 'http://en.wikipedia.org/wiki/World_population' | > url <- 'http://en.wikipedia.org/wiki/World_population' |
| > tbls <- readHTMLTable(url) | > tbls <- readHTMLTable(url) |
| | </code> |
| | |
| | The above not working for me. :( |
| | |
| | <code>library(httr) |
| | url <- 'http://en.wikipedia.org/wiki/World_population' |
| | tables <- GET(url) |
| | tables <- readHTMLTable(rawToChar(tables$content)) |
| </code> | </code> |
| |
