How to expand a dataset by 1 week backward

[Francois Durant]

Hi,

I would like to expand the dataset by one period backward with a weekly time series dataset. Here is what I have:

* Example generated by -dataex-. For more info, type help dataex
clear
input double(w_date closeanonymity)
3212  -.07453440740494499
3213     -.11201581072541
3214   .04650582362758038
3215   .09057059803945666
3216 .0009825186085834492
3217  -.16465546472929637
3218  -.10327840076331218
3219  -.15560464683759367
3220   -.2868120202786998
3221   -.3258841641309259
3222   -.3327205765329304
3223  -.31961745290325916
3224  -.26222046986742675
3225  -.20663110145042796
3226   -.3206685932589224
3227  -.35852332182981206
3228   -.4651596783969958
3229   -.4637146143870273
3230   -.4619871204112953
3231   -.4574751448500801
3232   -.3093820467796068
3233  -.26106590245418315
3234   -.3398592328611313
3235   -.3664738704478687
3236   -.4188043793908631
3237   -.4033281009480306
3238   -.4124801422354588
3239  -.43229760801132255
3240  -.37120071672328536
3241    -.450118623231906
3242   -.5865024613785637
3243   -.5890292276520772
3244   -.6186922442393452
3245   -.5770453072124755
3246   -.5635392246014329
3247    -.496780592116965
3248   -.5032697211266051
3249   -.5282170209371102
3250   -.5643123612949275
3251    -.609999052559115
3252   -.6010931502084521
3253   -.5752631673809323
3254   -.5590466609705688
3255   -.5776376572340056
3256   -.5438718491198751
3257   -.5668957088891466
3258   -.5831774631993886
3259   -.6187178329476606
3260    -.646653088129276
3261   -.6804035616109922
3262   -.6803588878861471
end
format %tw w_date

That is, I would like to create a first row with w_date == 2021w40 and all other empty columns. Can someone help? Thanks.

[Øyvind Snilsberg]

insobs 1
replace w_date = 3211 in l

[Francois Durant]

Thanks Øyvind! However I need to add the observation at the beginning of the sample and not at the end.

Plus, the initial date will change as I am trying different samples. Is there any way to generate the first date automatically without inputting "3211"? Thanks!

[Øyvind Snilsberg]

insobs 1, before(1)
replace w_date = w_date[_n+1] - 1 in 1