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From: ishii.mitsuo.titanium on 18 May 2010 06:12
Hi

I have a problem.


I have a list.

testList={ {11,{2,3}},{21,{3,4}},{34,{5,6}},{51,{7,8}} }

1) From this list, select any element list such as {x,{3,4}},

where X is an arbitrary number.

In general, position of {x,{3,4}} in "testList" is not fixed.

2) Select any element list such as {x,{3,4}} and then exchange {x,{3,4}} to {100,{3,4}}.

3)Make a new list finally.

testListNew={ {11,{2,3}},{100,{3,4}},{34,{5,6}},{51,{7,8}} }

Please teach me how to solve.

Thanks in advance.

Mitsuo Ishii

From: Bob Hanlon on 19 May 2010 07:00

testList = {{11, {2, 3}}, {21, {3, 4}}, {34, {5, 6}}, {51, {7, 8}}, {77, {3,
4}}};

Cases[testList, {_, {3, 4}}]

{{21, {3, 4}}, {77, {3, 4}}}

or

Select[testList, #[[2]] == {3, 4} &]

{{21, {3, 4}}, {77, {3, 4}}}

Flatten[Position[testList, {_, {3, 4}}]]

{2,5}

However, none of this is needed. Just use

testList /. {_, {3, 4}} -> {100, {3, 4}}

{{11, {2, 3}}, {100, {3, 4}},
{34, {5, 6}}, {51, {7, 8}},
{100, {3, 4}}}


Bob Hanlon

---- ishii.mitsuo.titanium(a)nsc.co.jp wrote:

=============
Hi

I have a problem.


I have a list.

testList={ {11,{2,3}},{21,{3,4}},{34,{5,6}},{51,{7,8}} }

1) From this list, select any element list such as {x,{3,4}},

where X is an arbitrary number.

In general, position of {x,{3,4}} in "testList" is not fixed.

2) Select any element list such as {x,{3,4}} and then exchange {x,{3,4}} to {100,{3,4}}.

3)Make a new list finally.

testListNew={ {11,{2,3}},{100,{3,4}},{34,{5,6}},{51,{7,8}} }

Please teach me how to solve.

Thanks in advance.

Mitsuo Ishii



From: Raffy on 19 May 2010 07:01
On May 18, 3:12 am, ishii.mitsuo.titan...(a)nsc.co.jp wrote:
> Hi
>
> I have a problem.
>
> I have a list.
>
> testList={ {11,{2,3}},{21,{3,4}},{34,{5,6}},{51,{7,8}} }
>
> 1) From this list, select any element list such as {x,{3,4}},
>
> where X is an arbitrary number.
>
> In general, position of {x,{3,4}} in "testList" is not fixed.
>
> 2) Select any element list such as {x,{3,4}} and then exchange {x,{3,4}} to {100,{3,4}}.
>
> 3)Make a new list finally.
>
> testListNew={ {11,{2,3}},{100,{3,4}},{34,{5,6}},{51,{7,8}} }
>
> Please teach me how to solve.
>
> Thanks in advance.
>
> Mitsuo Ishii

ClearAll[sub];
sub[expr_, find_, replace_] := Replace[expr, {_, find} -> {replace,
find}, {1}];

sub[{{11, {2, 3}}, {21, {3, 4}}, {34, {5, 6}}, {51, {7, 8}}}, {3, 4},
100]
==> {{11, {2, 3}}, {100, {3, 4}}, {34, {5, 6}}, {51, {7, 8}}}

From: Bill Rowe on 19 May 2010 07:02
On 5/18/10 at 6:12 AM, ishii.mitsuo.titanium(a)nsc.co.jp wrote:

>I have a list.

>testList={ {11,{2,3}},{21,{3,4}},{34,{5,6}},{51,{7,8}} }

>1) From this list, select any element list such as {x,{3,4}},

>where X is an arbitrary number.

either

In[5]:= Cases[testList, {_, {3, 4}}]

Out[5]= {{21, {3, 4}}}

or

In[6]:= Select[testList, Last@# === {3, 4} &]

Out[6]= {{21, {3, 4}}}

will do this

>In general, position of {x,{3,4}} in "testList" is not fixed.

>2) Select any element list such as {x,{3,4}} and then exchange
>{x,{3,4}} to {100,{3,4}}.

>3)Make a new list finally.

>testListNew={ {11,{2,3}},{100,{3,4}},{34,{5,6}},{51,{7,8}} }

This last can be accomplished in one step as:

In[7]:= testList /. {_, {3, 4}} -> {100, {3, 4}}

Out[7]= {{11, {2, 3}}, {100, {3, 4}}, {34, {5, 6}},
{51, {7, 8}}}


From: Peter Breitfeld on 19 May 2010 07:02
ishii.mitsuo.titanium(a)nsc.co.jp wrote:

> Hi
>
> I have a problem.
>
>
> I have a list.
>
> testList={ {11,{2,3}},{21,{3,4}},{34,{5,6}},{51,{7,8}} }
>
> 1) From this list, select any element list such as {x,{3,4}},
>
> where X is an arbitrary number.
>
> In general, position of {x,{3,4}} in "testList" is not fixed.
>
> 2) Select any element list such as {x,{3,4}} and then exchange {x,{3,4}} to {100,{3,4}}.
>
> 3)Make a new list finally.
>
> testListNew={ {11,{2,3}},{100,{3,4}},{34,{5,6}},{51,{7,8}} }
>
> Please teach me how to solve.
>
> Thanks in advance.
>
> Mitsuo Ishii
>

First search, where the member is

pos=Position[testList,{_,{3,4}}]

newlist=ReplacePart[testList, pos->{100,{3,5}}]

--
_________________________________________________________________
Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de

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