Day 13 R on Coursera , Reading Datasets

Attributes in R - names, length, class, dimensions
COmplex Vectors 1+0i imaginary number
Vector function vector()
Coercion when mixing vectors
Explicit coercion
as.numeric(),as.logical(),as.character(),as.complex()
attributes(),dim()
Attach 2 columns or 2 rows , cbind(),rbind()
table(x)
is.na(),is.nan()
nrow() ,ncol()

Reading strings that contain whitespace into R from tab delimited .txt file

http://stackoverflow.com/questions/11199496/reading-strings-that-contain-whitespace-into-r-from-tab-delimited-txt-file

Difference between read.table and read.delim functions

http://stackoverflow.com/questions/10599708/difference-between-read-table-and-read-delim-functions

read.delim(file, header = FALSE, sep = "\t", quote = "\"",
           dec = ".", fill = TRUE, comment.char = "", ...)
read.delim2(file, header = TRUE, sep = "\t", quote = "\"",
          dec = ",", fill = TRUE, comment.char = "", ...)

Only read limited number of columns

http://stackoverflow.com/questions/5788117/only-read-limited-number-of-columns

Setting nrows= helps in reducing the RAM that would be required to read the large datasets,

below is the calculation, also generally twice this calculation is required.