Extract the name of a point with Regular Expression

Question

I have a list of points as strings in the form

{"A1=(345.2345,3423.1)","B=(2123,97.123)","KX=(2144.546,-4455)"}

and I would like to extract the names using RegularExpression. For a single point I tried

StringCases["A1=(345.2345,3423.1)", RegularExpression["^.+\\="]]

but the output is

{"A1="}

How can I extract only the name (everything that is on the left of "=" at the beginning of the string) without the character "=" itself?

A slight variant of the solution already given: StringCases[lst, RegularExpression["(^.+)[=]"]:>"$1"] where 'lst=your_list — user1066, Mar 18, 2020 at 9:43
In addition, maybe consider StringSplit[lst, "="][[All,1]] or StringSplit[lst, RegularExpression["="]][[All,1]] — user1066, Mar 18, 2020 at 11:05

kglr · Accepted Answer · 2020-03-18 09:20:58Z

5

ClearAll[f]
f = StringCases[RegularExpression["(^.+)="] :> "$1"] 

f /@ {"A1=(345.2345,3423.1)",  "B=(2123,97.123)", "KX=(2144.546,-4455)"}

{{"A1"}, {"B"}, {"KX"}}

answered Mar 18, 2020 at 9:20

kglr

356k18 gold badges418 silver badges791 bronze badges

Add a comment |

Alexey Popkov · Accepted Answer · 2020-03-18 12:55:46Z

4

ClearAll[f]
f = StringCases[RegularExpression["^[^=]+(?==)"]];

f /@ {"A1=(345.2345,3423.1)", "B=(2123,97.123)", "KX=(2144.546,-4455)"}

{{"A1"}, {"B"}, {"KX"}}

answered Mar 18, 2020 at 12:55

Alexey Popkov

60.8k6 gold badges147 silver badges360 bronze badges

Add a comment |

Rohit Namjoshi · Accepted Answer · 2020-03-18 18:31:54Z

4

Another way, without using regular expressions

StringSplit[#, "="] & /* First /@ {"A1=(345.2345,3423.1)", "B=(2123,97.123)", "KX=(2144.546,-4455)"}

{* {"A1", "B", "KX"} *)

answered Mar 18, 2020 at 18:31

Rohit Namjoshi

9,8736 gold badges15 silver badges62 bronze badges

Add a comment |

3 Answers 3