Get new variable based on the average of a column - Matlab

I have a cell array variable with 15 columns and about 200 000 rows. These cell array, is sorted by year (C1) and then by a code (C2). For instance, in this example in only present 3 years and 2 codes:

C1   C2 C3   C4  C5
1997  3 AA 3421 0.4
1997 11 AB  789 2.1
1998  3 FC 3421 0.1
1998  3 NU 3421 0.6
1998 11 AB  789   0
1998 11 NT  789 0.4
1999  3 NU   42 0.3
1999 11 NT   17 0.5
2000  3 FC   42 0.8
2000  3 NO   42 1.2
2000 11 NT   17 0.9

I would like to get a new variable giving me the average of the values in C5 for each different code in C2, in year t (e.g.: 1999) and 2 previous years (e.g.: 1997 & 1998), independently of the values/strings in columns C3 and C4. In this example I would obtain:

C2 C3   NEW
 3 1997  - % There is no data prior to 1997 so I cannot calculate the average for year t, t-1 & t-2
11 1997  -
 3 1998  -
11 1998  -
 3 1999 0,35 %(0.4+0.1+0.6+0.3)/4
11 1999 0,75 %(2.1+0+0.4+0.5)/4
 3 2000 0,6 %(0.1+0.6+0.3+0.8+1.2)/5
11 2000 0,45 %(0+0.4+0.5+0.9)/4

Can someone help? Thanks.

[Sara]

Which columns are strings and which are numbers in your cell array?

[Maria]

Sara Columns 3, 10, 11 and 12 are strings, all the rest is numbers.

[Sara]

How can you have C5 as number in matlab? You mean you actually have 0.4 and so on in your cell array (the comma is not the decimal sign in matlab)? The type influences how you treat variables, that's why I'm asking.

[Maria]

I am sorry. In Matlab I have the decimal sign. When I built the example I wrote 'commas' instead. I will edit it.

Answer 1

[Sara]

See file

[Maria]

I am sorry. Where can I get to see the file?

[Sara]

Forgot to press the attach button :) See above

[Maria]

I tried your code, it gives the following error:

Error using  & 
Matrix dimensions must agree.

I am running out of time now, but I will check what's wrong. I will let you know later on. Thanks

[Sara]

Works for me with the input provided. May want to attach the whole input to your post if the program fails.