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Eliminate empty elements from a list with a specific pattern

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Eliminate empty elements from a list with a specific pattern

List operation on specific elementsSelect elements from list with given headSelecting elements from a list with nullsReplace empty list elements with patternReplacing Non-Constant Elements from List with Patternselecting elements from a list with two numbersRemoving elements of a specific length from a listEliminate types of elements from the listListPlot3D with empty matrix elementsDelete a large pattern from one list

3

1

$begingroup$

I am really new in this patterns part of Mathematica. Basically what I need to do is eliminate null elements from a list but that has a specific name before the empty element. For example, my list is:

list="a11-b11-", "a12-b11-1", "c11-d22-", "d33-c22-2"

and I need to obtain

list="a12-b11-1", "d33-c22-2"

The list was created using

list = Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> 
 ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]], 
 i, 1, 4, j, 1, 4], 1]

and for some values it writtes because there is not a value equal to $0.5$. Until now I have been able to do it term by term as

list//."a11-b11-"-> Sequence[]

but the real list contains a lot of elements and could be almost impossible to do it that way to solve the problem. I think my main problem is that I am not sure how to specify the pattern search (something like " *-name " in gnu/linux). Is there a wise way to do this?. Thanks in advance.

list-manipulation filtering

share|improve this question

edited 6 hours ago

Roman

4,65511128

asked 12 hours ago

morsmors

496

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Have a look at DeleteCases and StringMatchQ or StringContainsQ.
  $endgroup$
  – b.gatessucks
  11 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I think it would be more efficient to first filter out the unwanted cases in the int function, and then construct strings only from the remaining ones.
  $endgroup$
  – Roman
  11 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  @b.gatessucks Thank you, I will look those option in Mathematica.
  $endgroup$
  – mors
  11 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  @Roman You are right, but I am new ih this cases stuf in Mathematica and I did no know how to do it when I created the list.
  $endgroup$
  – mors
  11 hours ago
  

  
  
  
  

add a comment | 

3

1

$begingroup$

I am really new in this patterns part of Mathematica. Basically what I need to do is eliminate null elements from a list but that has a specific name before the empty element. For example, my list is:

list="a11-b11-", "a12-b11-1", "c11-d22-", "d33-c22-2"

and I need to obtain

list="a12-b11-1", "d33-c22-2"

The list was created using

list = Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> 
 ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]], 
 i, 1, 4, j, 1, 4], 1]

and for some values it writtes because there is not a value equal to $0.5$. Until now I have been able to do it term by term as

list//."a11-b11-"-> Sequence[]

but the real list contains a lot of elements and could be almost impossible to do it that way to solve the problem. I think my main problem is that I am not sure how to specify the pattern search (something like " *-name " in gnu/linux). Is there a wise way to do this?. Thanks in advance.

list-manipulation filtering

share|improve this question

edited 6 hours ago

Roman

4,65511128

asked 12 hours ago

morsmors

496

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Have a look at DeleteCases and StringMatchQ or StringContainsQ.
  $endgroup$
  – b.gatessucks
  11 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I think it would be more efficient to first filter out the unwanted cases in the int function, and then construct strings only from the remaining ones.
  $endgroup$
  – Roman
  11 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  @b.gatessucks Thank you, I will look those option in Mathematica.
  $endgroup$
  – mors
  11 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  @Roman You are right, but I am new ih this cases stuf in Mathematica and I did no know how to do it when I created the list.
  $endgroup$
  – mors
  11 hours ago
  

  
  
  
  

add a comment | 

$begingroup$

I am really new in this patterns part of Mathematica. Basically what I need to do is eliminate null elements from a list but that has a specific name before the empty element. For example, my list is:

list="a11-b11-", "a12-b11-1", "c11-d22-", "d33-c22-2"

and I need to obtain

list="a12-b11-1", "d33-c22-2"

The list was created using

list = Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> 
 ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]], 
 i, 1, 4, j, 1, 4], 1]

and for some values it writtes because there is not a value equal to $0.5$. Until now I have been able to do it term by term as

list//."a11-b11-"-> Sequence[]

but the real list contains a lot of elements and could be almost impossible to do it that way to solve the problem. I think my main problem is that I am not sure how to specify the pattern search (something like " *-name " in gnu/linux). Is there a wise way to do this?. Thanks in advance.

list-manipulation filtering

share|improve this question

edited 6 hours ago

Roman

4,65511128

asked 12 hours ago

morsmors

496

$endgroup$

list="a11-b11-", "a12-b11-1", "c11-d22-", "d33-c22-2"

list="a12-b11-1", "d33-c22-2"

list = Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> 
 ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]], 
 i, 1, 4, j, 1, 4], 1]

list//."a11-b11-"-> Sequence[]

share|improve this question

edited 6 hours ago

Roman

4,65511128

asked 12 hours ago

morsmors

496

share|improve this question

edited 6 hours ago

Roman

4,65511128

asked 12 hours ago

morsmors

496

edited 6 hours ago

Roman

4,65511128

edited 6 hours ago

Roman

4,65511128

asked 12 hours ago

morsmors

496

asked 12 hours ago

morsmors

496

2 Answers
2

active

oldest

votes

7

$begingroup$

If the list elements are strings, as it appears after your comment, you can use Select with a string pattern:

list = "a11-b11-", "a12-b11-1", "c11-d22-", "d33-c22-2";
Select[list, Not@*StringMatchQ[__ ~~ ""]]

"a12-b11-1", "d33-c22-2"

You could also Select before making the strings:

L = DeleteCases[
 Flatten[
 Table[
 namea[[i]], nameb[[j]], Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1],
 i, 4, j, 4],
 1],
 _, _, ];

and then make these into strings:

StringRiffle[ToString /@ #, "-"] & /@ L

I can't check this because you didn't supply functioning code.

share|improve this answer

edited 7 hours ago

answered 11 hours ago

RomanRoman

4,65511128

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Thank you, I forgot to specify the way the list is created. I create the list as 'list = Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]], i, 1, 4, j, 1, 4], 1] '
  $endgroup$
  – mors
  11 hours ago
  
  

  
  
  
  

add a comment | 

0

$begingroup$

In 10.1, two functions were added to handle a pair of very common cases: StringStartsQ and StringEndsQ which return True if the string matches a pattern at the beginning or end, respectively. So, while Roman's answer gives you the full general form, most of the pattern can be eliminated by using

list = "a11-b11-", "a12-b11-1", "c11-d22-", "d33-c22-2";
Select[list, Not@*StringEndsQ[""]]

instead.

share|improve this answer

answered 5 hours ago

rcollyerrcollyer

28.6k674166

$endgroup$

add a comment | 

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7

$begingroup$

If the list elements are strings, as it appears after your comment, you can use Select with a string pattern:

list = "a11-b11-", "a12-b11-1", "c11-d22-", "d33-c22-2";
Select[list, Not@*StringMatchQ[__ ~~ ""]]

"a12-b11-1", "d33-c22-2"

You could also Select before making the strings:

L = DeleteCases[
 Flatten[
 Table[
 namea[[i]], nameb[[j]], Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1],
 i, 4, j, 4],
 1],
 _, _, ];

and then make these into strings:

StringRiffle[ToString /@ #, "-"] & /@ L

I can't check this because you didn't supply functioning code.

share|improve this answer

edited 7 hours ago

answered 11 hours ago

RomanRoman

4,65511128

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Thank you, I forgot to specify the way the list is created. I create the list as 'list = Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]], i, 1, 4, j, 1, 4], 1] '
  $endgroup$
  – mors
  11 hours ago
  
  

  
  
  
  

add a comment | 

7

$begingroup$

If the list elements are strings, as it appears after your comment, you can use Select with a string pattern:

list = "a11-b11-", "a12-b11-1", "c11-d22-", "d33-c22-2";
Select[list, Not@*StringMatchQ[__ ~~ ""]]

"a12-b11-1", "d33-c22-2"

You could also Select before making the strings:

L = DeleteCases[
 Flatten[
 Table[
 namea[[i]], nameb[[j]], Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1],
 i, 4, j, 4],
 1],
 _, _, ];

and then make these into strings:

StringRiffle[ToString /@ #, "-"] & /@ L

I can't check this because you didn't supply functioning code.

share|improve this answer

edited 7 hours ago

answered 11 hours ago

RomanRoman

4,65511128

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Thank you, I forgot to specify the way the list is created. I create the list as 'list = Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]], i, 1, 4, j, 1, 4], 1] '
  $endgroup$
  – mors
  11 hours ago
  
  

  
  
  
  

add a comment | 

$begingroup$

If the list elements are strings, as it appears after your comment, you can use Select with a string pattern:

list = "a11-b11-", "a12-b11-1", "c11-d22-", "d33-c22-2";
Select[list, Not@*StringMatchQ[__ ~~ ""]]

"a12-b11-1", "d33-c22-2"

You could also Select before making the strings:

L = DeleteCases[
 Flatten[
 Table[
 namea[[i]], nameb[[j]], Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1],
 i, 4, j, 4],
 1],
 _, _, ];

and then make these into strings:

StringRiffle[ToString /@ #, "-"] & /@ L

I can't check this because you didn't supply functioning code.

share|improve this answer

edited 7 hours ago

answered 11 hours ago

RomanRoman

4,65511128

$endgroup$

list = "a11-b11-", "a12-b11-1", "c11-d22-", "d33-c22-2";
Select[list, Not@*StringMatchQ[__ ~~ ""]]

L = DeleteCases[
 Flatten[
 Table[
 namea[[i]], nameb[[j]], Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1],
 i, 4, j, 4],
 1],
 _, _, ];

StringRiffle[ToString /@ #, "-"] & /@ L

share|improve this answer

edited 7 hours ago

answered 11 hours ago

RomanRoman

4,65511128

answered 11 hours ago

RomanRoman

4,65511128

answered 11 hours ago

RomanRoman

4,65511128

0

$begingroup$

In 10.1, two functions were added to handle a pair of very common cases: StringStartsQ and StringEndsQ which return True if the string matches a pattern at the beginning or end, respectively. So, while Roman's answer gives you the full general form, most of the pattern can be eliminated by using

list = "a11-b11-", "a12-b11-1", "c11-d22-", "d33-c22-2";
Select[list, Not@*StringEndsQ[""]]

instead.

share|improve this answer

answered 5 hours ago

rcollyerrcollyer

28.6k674166

$endgroup$

add a comment | 

0

$begingroup$

In 10.1, two functions were added to handle a pair of very common cases: StringStartsQ and StringEndsQ which return True if the string matches a pattern at the beginning or end, respectively. So, while Roman's answer gives you the full general form, most of the pattern can be eliminated by using

list = "a11-b11-", "a12-b11-1", "c11-d22-", "d33-c22-2";
Select[list, Not@*StringEndsQ[""]]

instead.

share|improve this answer

answered 5 hours ago

rcollyerrcollyer

28.6k674166

$endgroup$

add a comment | 

$begingroup$

In 10.1, two functions were added to handle a pair of very common cases: StringStartsQ and StringEndsQ which return True if the string matches a pattern at the beginning or end, respectively. So, while Roman's answer gives you the full general form, most of the pattern can be eliminated by using

list = "a11-b11-", "a12-b11-1", "c11-d22-", "d33-c22-2";
Select[list, Not@*StringEndsQ[""]]

instead.

share|improve this answer

answered 5 hours ago

rcollyerrcollyer

28.6k674166

$endgroup$

list = "a11-b11-", "a12-b11-1", "c11-d22-", "d33-c22-2";
Select[list, Not@*StringEndsQ[""]]

share|improve this answer

answered 5 hours ago

rcollyerrcollyer

28.6k674166

answered 5 hours ago

rcollyerrcollyer

28.6k674166

answered 5 hours ago

rcollyerrcollyer

28.6k674166