| tsvGetLines {tsvio} | R Documentation |
Read matching lines from a tsv file, using a pre-computed index file.
Description
This function reads lines that match the given patterns from a TSV file with the assistance of a pre-computed index file to the start of each row.
Usage
tsvGetLines(filename, indexfile, patterns, findany = TRUE)
Arguments
filename |
The name (and path) of the file containing the data to index. |
indexfile |
The name (and path) of the file to which the index will be written. |
patterns |
A vector of strings containing the string to match against the index entries. Only lines with keys that exactly match at least one pattern string are returned. |
findany |
If false, all patterns must be matched. If true (default) at least one pattern must match. |
Details
The index file must have been created by tsvGenIndex and the data file must not have changed since the index file was created.
Value
A string vector whose first element is the first line from data file. Subsequent elements of the vector are lines from the data file whose labels match an entry in patterns.
See Also
tsvGenIndex, tscGetData
Examples
datafile = tempfile("data");
df <- data.frame(C1 = c("Foo", "Boing", "The"), C2 = c("Bar", "Boing", "End"));
rownames(df) <- c("R1", "R2", "R3");
write.table(df, file=datafile, sep="\t", quote=FALSE, row.names=TRUE, col.names=TRUE);
indexfile = tempfile("index");
tsvGenIndex (datafile, indexfile);
tsvGetLines (datafile, indexfile, c("R1", "R3"))