Re: Cases and Nonatomic expression

*To*: mathgroup at smc.vnet.net*Subject*: [mg56764] Re: [mg56718] Cases and Nonatomic expression*From*: János <janos.lobb at yale.edu>*Date*: Thu, 5 May 2005 06:02:41 -0400 (EDT)*References*: <200505040434.AAA06285@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On May 4, 2005, at 12:34 AM, Swati Shah wrote: > Hi Everyone > > I have a list > k = {{1,1,2,2,3}, {1,2,2,2,3}, {2,3,3,3,3}, {5,2,2,2,1}, {6,1,1,1,1}, > {6,1,1,1,1}} > > If the first element of the sublist is 1 I want to append the > sublist to > g1, if it starts with 2 then append g2 or starts with 6 then append > to g6 > > I used cases and did the following: > m1 = Cases[k, {1, __}]; > m2 = Cases[k, {2, __}]; > m3 = Cases[k, {3, __}]; > m4 = Cases[k, {4, __}]; > m5 = Cases[k, {5, __}]; > m6 = Cases[k, {6, __}]; > > However, instead of typing each one of these lines separately, it > would be nice to use just a simple Map or something or a for loop (as > I have more than 50 different start values) > > I tried the following 2 ways: > > a) using a for loopFor [i = 1, i < 7, > t = "g" <> ToString [i]; > Print [t]; > t = Cases [k, {i, __}]; > Print [t] > i++] > > However outside the for loop the values of g1..g6 is empty. > > b) I tried using MAP (in the similar way as the for) > > But I get the following error: > Append::normal: Nonatomic expression expected at position 1 in > Append[g1,{1, \ > 168, 0.695873, 6.54462, 62.4578, 82.5056}] > > > Any suggestions as to how I can get this working? > > Thanks in advance > > Swati Swati, Here is my try: In[65]:= col = Last[Reap[i = 1; While[i <= Length[k], Sow[k[[i]], k[[i,1]]]; i++; ]]] Out[65]= {{{1, 1, 2, 2, 3}, {1, 2, 2, 2, 3}}, {{2, 3, 3, 3, 3}}, {{5, 2, 2, 2, 1}}, {{6, 1, 1, 1, 1}, {6, 1, 1, 1, 1}}} János

**References**:**Cases and Nonatomic expression***From:*Swati Shah <swatshah@gmail.com>