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str_get_cols

Returns an array of substrings, given a start and end index into the given string.

Available in version 5.1.1 and later.

Prototype

	function str_get_cols (
		string_val    : string,   
		start_col [1] : integer,  
		end_col   [1] : integer   
	)

	return_val [dimsizes(string_val)] :  string

Arguments

string_val

An array of strings of any dimensionality.

start_col
end_col

Scalar integers representing the start column and end column to be grabbed from a string. Numbering is 0-based, so the first column is 0.

Description

This function returns an array of substrings with the same dimensionality as the input strings, but with the strings subscripted from start_col to end_col.

You can use negative index values to indicate a count from the end of the string. For example, -1 represents the last character in a string, -2 the second-to-the-last character, etc.

If end_col is greater than start_col, then the substring will be reversed (see example below).

If just one of start_col and/or end_col are out-of-bounds, then the string will be subscripted only to the end or beginning as appropriate. If both are out-of-bounds, then an empty string ("") will be returned.

If input strings are missing, then missing values will be returned.

See Also

str_fields_count, str_get_field

Examples

Example 1

Assume you have an ASCII file, "asc3.txt": 

200306130209   0.38   25.28 10088 233.95   6  92  9.99  9.99 99999.0   0.0 -9.99 167.9 p p p 1782  BOS_1  ATL 3              
200306130209   0.38   25.28 10088 233.95   6  92  9.99  9.99 99999.0   0.0 -9.99 167.9 p p p 1782  ORD_2  ATL 3              
200306122341 -45.10  168.70   914 279.35   4 272  9.99  9.99     1.1   0.0  0.01 -99.9 p p p 4552  DTW_3  MSP 3              
200306122341 -45.10  168.70   914 279.35   4 272  9.99  9.99     1.1   0.0  0.01 -99.9 p p p 4552  SDF_4  MHR 3
Use str_fields_count to count the number of fields separated by one or more spaces, str_get_field to retrieve the fields, and then str_get_cols to retrieve subsets of these fields: 
 flnm = "asc3.txt"
 strs = asciiread(flnm,-1,"string")

 delim = " "
 nfields = str_fields_count(strs(0), delim)   ; Count the fields separated
                                              ; by one or more spaces.
 print(nfields)                               ; nfields = 20

 field = 1
 subStrings = str_get_field(strs, field, delim)
 print(subStrings)              ; (/"200306130209","200306130209",...,/)

 year = str_get_cols(subStrings, 0, 3)
 print(year)                   ; (/"2003","2003","2003","2003"/)

 month = str_get_cols(subStrings, 4, 5)
 print(month)                  ; (/"06","06","06","06"/)

 day = stringtoint(str_get_cols(subStrings, 6, 7)
 print(day)                    ; (/13,13,12,12/)

 hour = stringtoint(str_get_cols(subStrings, 8, 9))
 print(hour)                   ; (/2,2,23,23)

 minute = stringtoint(str_get_cols(subStrings, 10, 11))
 print(minute)                  ; (/9,9,41,41/)
Example 2

Assume you have the same ASCII file and the same strs arrays as in example 1, but that you want to read in the first 12 characters and reverse them: 

 date = str_get_cols(strs, 11, 0)
 print(date)                        ; (/"902031603002","902031603002",.../)
To read in the second-to-the-last field, you can do this one of two ways: 
 field = nfields-1
 subStrings = str_get_field(strs, field, delim)
 print(subStrings)              ; (/"ATL","ATL","MSP","MHR"/)
Or: 
 subStrings = str_get_cols(strs,-5,-3)
 print(subStrings)              ; (/"ATL","ATL","MSP","MHR"/)
This second method is only good if you don't have extra whitespace at the end of your lines in the file.