[R] Finding strings in a dataset

Avi Gross @v|gro@@ @end|ng |rom ver|zon@net
Sun May 16 00:54:40 CEST 2021


What do you mean by a 2-D dataset? You say some columns contain strings so
it does not sound like you are using a matrix as then  ALL columns would be
of the same type.

So are you using a data.frame or tibble or something you made on your own?

Can you address one column at a time and would that be of type vector? Some
methods work fairly easily on those and some also on lists.

Once you have that vector, there are quite a few ways to find what you want.
Is it fixed text like looking for an exact full match so it would be
something like "theta" to be matched in full, or would you want to match
"the" and both "theta" and "lathe" would match? Or are you matching a
pattern that is more complex like looking for all text that has two vowels
in a row in it?

Once you figure out what you have and what you want, how do you want to
identify what you are looking for? Will there be one match or possibly many
or even all? Many methods will return a TRUE/FALSE vector of the same length
or the integer offset of a match such as telling you it is the fifth item.

R has collections of string functions including in packages like
stringr/stringi that deal well with many things you might need. For matching
patterns, there is a family of functions using "grep" and so on.

Good luck.

-----Original Message-----
From: R-help <r-help-bounces using r-project.org> On Behalf Of Tuhin Chakraborty
Sent: Saturday, May 15, 2021 1:08 PM
To: r-help using r-project.org
Subject: [R] Finding strings in a dataset

How can I find the location of string data in my 2D dataset? spec(Dataset)
will reveal the columns that contain the strings. But can I know where
exactly the string values are in the column?

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