Return any string of n contiguous numbers from a column-CodePudding

Suppose I have a dataset:

Have:

example1 example2
11-2001-6 st3829s
11-2001-6 s8290s
11-201-6 sts39

Want:

example1 example2
2001 3829
2001 8290
NA NA

I want to output the numbers that are 4 contiguous numbers or n numbers (specify length). If no group of 4 numbers occurs together return NA.

CodePudding user response：

First Things we are talking about regular expression. Second i will solve this using PHP language and you should find the solution for your program language

preg_match_all('/[0-9][0-9][0-9][0-9]/', '11-2001-6 st3829s', $output_array);

this will output

array(1
0   =>  array(2
0   =>  2001
1   =>  3829
)
)

but if you path

preg_match_all('/[0-9][0-9][0-9][0-9]/', '11-201-6 sts39', $output_array);

this will output

array(1
0   =>  array()
)

so you have check the output and if it empty array you have return NA

CodePudding user response：

We may use str_extract and mutate_all

library(stringr)
library(dplyr)
mutate_all(df,  ~str_extract(., pattern= "\\d{4}"))
 example1 example2
1     2001     3829
2     2001     8290
3     <NA>     <NA>