Reading specific lines from a csv file in R
1 answer
Assuming the dates are in the first column of your dataset (and you are on a Unix-like computer), you can do something like this:
dates <- paste0(c("2015-06-01", "2015-06-16"), collapse = "|")
expr <- paste0("grep -E '(", dates, "),.+' tmpcsv.csv", collapse = "")
##
R> data.table::fread(expr)
V1 V2
1: 2015-06-16 -1.6866933
2: 2015-06-16 1.3686023
3: 2015-06-01 -0.2257710
4: 2015-06-16 -1.0185754
5: 2015-06-01 0.3035286
6: 2015-06-01 2.0500847
7: 2015-06-01 -0.4910312
If not, you will have to change the regex accordingly.
Data:
set.seed(123)
##
df <- data.frame(
Date = Sys.Date() + floor(50*round(runif(50, -1, 1), 1)),
Value = rnorm(50)
)
write.csv(df, file = "tmpcsv.csv", row.names = FALSE)
##
+2
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