12 monthly data values to populate a series of 365 days

[matrix888]

I'd love the help of an excel guru on this! : )

I have a series of 12 monthly data values:

1/31/1999 0.155375
2/28/1999 0.179262
3/31/1999 0.179392
4/30/1999 0.178993
5/31/1999 0.17128
6/30/1999 0.139678
7/31/1999 0.15518
8/31/1999 0.15536
9/30/1999 0.17732
10/31/1999 0.117725
11/30/1999 0.134171
12/31/1999 0.149113

and also a series of the 365 days that comprise these 12 months.

I need to populate each of the 365 days within this period (1/1/1999-12/31/1999) with its corresponding value for the month, i.e. 1/21/1999 (and all days in Jan) will take 0.155375 and 5/4/1999 (and all days in May) will take 0.17128.

Does anybody know how I should set out my data and which formulas I need to use? I'd be very grateful for your help.

[hemesh]

hello matrix and welcome to the forum Kindly attach a sample book

to attach go to advance option ----> select paper clip icon OR go to manage attachment

[martindwilson]

with those in cols a1:a12 and values in b1:b12
then say your whole year list is in column a starting a14 to a378
then b14
=VLOOKUP(EOMONTH(A14,0),$A$1:$B$12,2,FALSE) filled down

[matrix888]

Sample book is attached, thanks guys.

[martindwilson]

f2 =VLOOKUP(EOMONTH(E2,0),$A$2:$B$13,2,FALSE)

[FDibbins]

If your table with the dates and values in sin A2:B13, and your daily dates are in D2, down, in C2, copied down, use this ARRAY formula...
=INDEX($B$2:$B$13,MATCH(MONTH(D2),MONTH($A$2:$A$13),0))
...confirmed by pressing CTRL+SHIFT+ENTER to activate the array, not just ENTER. You will know the array is active when you see curly braces { } appear around your formula. If you do not CTRL+SHIFT+ENTER you will get an error or a clearly incorrect answer. Press F2 on that cell and try again.

adjusted for your data...
=INDEX($B$2:$B$13,MATCH(MONTH(E2),MONTH($A$2:$A$13),0))
ARRAY entered

[matrix888]

Thank you.

[Xx7]

Try this..

[AlKey]

On your sheet in F2 and down

=LOOKUP(MONTH(E2),MONTH($A$2:$A$13),$B$2:$B$13)