Message-ID: <CADv2QyHxUBAsbLep2Sz45W4jGVU5vNKe3yvZTynx-Qk6iWhszA@mail.gmail.com>
Date: 2011-10-27T19:46:36Z
From: Dennis Murphy
Subject: Syntax Check: rshape2 melt()
In-Reply-To: <alpine.LNX.2.00.1110270825500.30779@salmo.appl-ecosys.com>
Try this, based on your small example:
> tds.a <- read.table(textConnection("
+ site sampdate param quant
+ 1 UDS-O 2006-12-06 TDS 10800
+ 4 STC-FS 1996-06-14 Cond 280
+ 7 UDS-O 2007-10-04 Mg 1620
+ 9 UDS-O 2007-10-04 SO4 7580
+ 19 JCM-10B 2007-06-21 Ca 79
+ 20 JCM-10B 2007-06-21 Cl 114"), header = TRUE, stringsAsFactors = FALSE)
> closeAllConnections()
# Define param so that all of its levels are represented:
tds.a <- within(tds.a, {
param = factor(param, levels = c('TDS', 'Cond', 'Mg', 'Ca',
'Cl', 'Na', 'SO4'))
sampdate = as.Date(sampdate) } )
library('reshape2')
dcast(tds.a, site + sampdate ~ param, value_var = 'quant')
# Result:
site sampdate TDS Cond Mg Ca Cl SO4
1 JCM-10B 2007-06-21 NA NA NA 79 114 NA
2 STC-FS 1996-06-14 NA 280 NA NA NA NA
3 UDS-O 2006-12-06 10800 NA NA NA NA NA
4 UDS-O 2007-10-04 NA NA 1620 NA NA 7580
HTH,
Dennis
On Thu, Oct 27, 2011 at 8:26 AM, Rich Shepard <rshepard at appl-ecosys.com> wrote:
> ?This is my first excursion into using reshape2 and I want to ensure that
> the melt() function call is syntactically correct.
>
> ?The unmodifed data frame is organized this way:
>
> head(tds.anal)
> ? ? ?site ? sampdate param quant
> 1 ? ?UDS-O 2006-12-06 ? TDS 10800
> 4 ? STC-FS 1996-06-14 ?Cond ? 280
> 7 ? ?UDS-O 2007-10-04 ? ?Mg ?1620
> 9 ? ?UDS-O 2007-10-04 ? SO4 ?7580
> 19 JCM-10B 2007-06-21 ? ?Ca ? ?79
> 20 JCM-10B 2007-06-21 ? ?Cl ? 114
>
> ?What I want looks like this:
>
> ? ?site ? ?sampdate ?TDS ? Cond ? Mg ?Ca ? Cl ?Na ?SO4
> ? UDS-O ?2006-12-06 ?10800 ?NA ? 1620 NA ? NA ?NA ?7580
>
> with the actual data for each param, of course.
>
> ?I've read the reshape.pdf, reshape2.pdf, the ?melt help page, and the
> ?melt.data.frame help page. I'm still unclear on the differences among
> measure.vars, variable.name, and value.name. After several attempts I have
> what may be what the melted tds.anal should look like:
>
> m.tds.anal <- melt(tds.anal, id.vars = c('site', 'sampdate', 'param'), \
> measure.vars = 'quant', value.name = 'quant', na.rm = F)
>>
>> head(m.tds.anal)
>
> ? ? site ? sampdate param variable quant
> 1 ? UDS-O 2006-12-06 ? TDS ? ?quant 10800
> 2 ?STC-FS 1996-06-14 ?Cond ? ?quant ? 280
> 3 ? UDS-O 2007-10-04 ? ?Mg ? ?quant ?1620
> 4 ? UDS-O 2007-10-04 ? SO4 ? ?quant ?7580
> 5 JCM-10B 2007-06-21 ? ?Ca ? ?quant ? ?79
> 6 JCM-10B 2007-06-21 ? ?Cl ? ?quant ? 114
>
> ?Is the melt() function call correct? Should the melted result look like
> the unmelted ("long" form in Paul Dalgaard's book) data with the additional
> 'variable' column containing 'quant' for each row?
>
> Rich
>
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