

Dear Arun and Rui,thanks indeed. it really worked out. 
i was wondering that can i draw the curve of stations "Sa" , "Ta" and remaining 67 stations on the same axis, for comparison? more precisely, taking years on axis, starting from the least year in my data and ending at latest, while taking population on y-axis?? for example,  in my present data the least year is 1955 and the latest is 1969. For "Sa" the curve must start from 1955 and should end at 1958 and for "Ta" the curve must start from 1966 and should end at 1969. 
thankyou very much indeed once again
eliza  

> Date: Mon, 17 Dec 2012 09:32:54 -0800
> From: smartpink111@yahoo.com
> Subject: Re: [R] mean of each month in data
> To: eliza_botto@hotmail.com
> CC: r-help@r-project.org
> 
> HI,
> 
> May be this helps:
> dat1<-read.table("Eliza.txt",sep="",header=TRUE,stringsAsFactors=FALSE)
> library(reshape2)
>  res<-lapply(split(dat1,dat1$st.),function(x) dcast(x,month~year,mean,value.var="population_in_million"))
> res
> $Sa
> #   month     1955 1956     1957 1958
> #1      1 2.400000  NaN      NaN  NaN
> #2      2 2.400000  NaN      NaN  NaN
> #3      3 2.266667  NaN      NaN  NaN
> #4      4      NaN  2.4      NaN  NaN
> #5      5      NaN  2.4      NaN  NaN
> #6      6      NaN  2.4      NaN  NaN
> #7      7      NaN  NaN 2.400000  NaN
> #8      8      NaN  NaN 2.400000  NaN
> #9      9      NaN  NaN 2.266667  NaN
> #10    10      NaN  NaN 2.400000  2.4
> #11    11      NaN  NaN      NaN  2.4
> #12    12      NaN  NaN      NaN  2.4
> 
> #$Ta
>  # month     1966 1967     1968 1969
> #1     1 2.400000  2.4 2.400000  2.4
> #2     2 2.400000  2.4 2.400000  2.4
> #3     3 2.266667  2.4 2.266667  2.4
> A.K.
> 
> 
> 
> 
> ----- Original Message -----
> From: eliza botto <eliza_botto@hotmail.com>
> To: "r-help@r-project.org" <r-help@r-project.org>
> Cc: 
> Sent: Monday, December 17, 2012 12:11 PM
> Subject: [R] mean of each month in data
> 
> 
> Dear R users,
> [in case the format of email is changed or you dont finf it easy to understand, i have attached a text file of my question]
> i have the data in the following format and i want to convert it in the 
> format given at the end.
> Ta ans Sa are the names of certain cities. there are 69 cities in my 
> data.
> column 1 is representing station name (i am writing the data of only 
> two cities for simplicity but actually, as i wrote, i have 69 cities 
> and the actuall table runs down very deep.) 
> Column 2 represnts the year for which the data is given (Actuall data 
> for each station is of different length but atleast of 24 years).
> Column 3 and 4 reprent the month and the day of the data. obviously 
> each year has 12 months and each month as different number of days, but 
> to make table easily understable only 3 months and 3 days of each month 
> are considered. febrary for leap years should also be considered.
> col5 represents population of that city
> 
> st. year month day population in million
> Ta 1966 1 1  2.4
> Ta 1966 1 2  2.4
> Ta 1966 1 3  2.4
> Ta 1966 2 1  2.4
> Ta 1966 2 2  2.4
> Ta 1966 2 3  2.4
> Ta 1966 3 1  2.3
> Ta 1966 3 2  2.2
> Ta 1966 3 3  2.3 
> Ta 1967 1 1  2.4
> Ta 1967 1 2  2.4
> Ta 1967 1 3  2.4
> Ta 1967 2 1  2.4
> Ta 1967 2 2  2.4
> Ta 1967 2 3  2.4
> Ta 1967 3 1  2.4
> Ta 1967 3 2  2.4
> Ta 1967 3 3  2.4
> Ta 1968 1 1  2.4
> Ta 1968 1 2  2.4
> Ta 1968 1 3  2.4
> Ta 1968 2 1  2.4
> Ta 1968 2 2  2.4
> Ta 1968 2 3  2.4
> Ta 1968 3 1  2.3
> Ta 1968 3 2  2.2
> Ta 1968 3 3  2.3 
> Ta 1969 1 1  2.4
> Ta 1969 1 2  2.4
> Ta 1969 1 3  2.4
> Ta 1969 2 1  2.4
> Ta 1969 2 2  2.4
> Ta 1969 2 3  2.4
> Ta 1969 3 1  2.4
> Ta 1969 3 2  2.4
> Ta 1969 3 3  2.4
> Sa 1955 1 1  2.4
> Sa 1955 1 2  2.4
> Sa 1955 1 3  2.4
> Sa 1955 2 1  2.4
> Sa 1955 2 2  2.4
> Sa 1955 2 3  2.4
> Sa 1955 3 1  2.3
> Sa 1955 3 2  2.2
> Sa 1955 3 3  2.3 
> Sa 1956 4 1  2.4
> Sa 1956 4 2  2.4
> Sa 1956 4 3  2.4
> Sa 1956 5 1  2.4
> Sa 1956 5 2  2.4
> Sa 1956 5 3  2.4
> Sa 1956 6 1  2.4
> Sa 1956 6 2  2.4
> Sa 1956 6 3  2.4
> Sa 1957 7 1  2.4
> Sa 1957 7 2  2.4
> Sa 1957 7 3  2.4
> Sa 1957 8 1  2.4
> Sa 1957 8 2  2.4
> Sa 1957 8 3  2.4
> Sa 1957 9 1  2.3
> Sa 1957 9 2  2.2
> Sa 1957 9 3  2.3 
> Sa 1957 10 1  2.4
> Sa 1958 10 2  2.4
> Sa 1958 10 3  2.4
> Sa 1958 11 1  2.4
> Sa 1958 11 2  2.4
> Sa 1958 11 3  2.4
> Sa 1958 12 1  2.4
> Sa 1958 12 2  2.4
> Sa 1958 12 3  2.4
> ...
> ...
> uptill 69th station
> 
> i want to convert the data in following format
> >Ta ## matrix for station Ta
> 1966   1967   1968   1969
> AVERAGE OF MONTH 1 AVERAGE OF MONTH 1 AVERAGE OF MONTH 1 AVERAGE OF MONTH 1
> AVERAGE OF MONTH 2 AVERAGE OF MONTH 2 AVERAGE OF MONTH 2 AVERAGE OF MONTH 2
> AVERAGE OF MONTH 3 AVERAGE OF MONTH 3 AVERAGE OF MONTH 3 AVERAGE OF MONTH 3
> ........
> ........
> AVERAGE OF MONTH 12 AVERAGE OF MONTH 12 AVERAGE OF MONTH 12 AVERAGE OF MONTH 12
> similar operation are to be done for "Sa" and the remaining 67 
> stations...
> which means i want to have 69 matrices, in which each column (number of 
> columns should be equal to number of years of data)  should contain 12 
> mean monthly values of population of each year. 
> 
> thanks in advance
> 
> eliza                           
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