Hi, I'm new here,
I'd like to map a set of values in a data frame to another set of values in
another frame (think a c++ map<>, a python dict or a hash lookup)
Specifically, I have a data frame of information about trading periods in the NZ
electricity market. For each period I have information about each bus (or node)
in the network. I'd like add a "column" to the data frame
containing the island that the bus is on.
I'm afraid my success at searching for an answer is restricted by not
knowing what this operation might be called in R, but I found a something on
stackoverflow [1] and tried the following:
map <- read.table("../node_islands.csv", header=TRUE,
sep=",")
map <- setNames(map$island, map$node)
periods$Island = map[periods$Bus]
Where after the first line, but before the second and third:
> map[1:3,]
node island
1 ABY0111 SI
2 ABY1101 SI
3 ADD0111 SI
and:
> periods[1:3, c("Date", "Period", "Bus",
"Price")]
Date Period Bus Price
1 2004-01-01 1 ABY0111 31.20
2 2004-01-01 1 ADD0111 32.43
3 2004-01-01 1 ADD0661 32.38
This seems to work (it fooled me for quite a while :-) ), but the following
check:
for (b in periods$Bus)
{
if (periods[periods$Bus == b, "Island"] != map[b])
{
print(b)
print(periods[periods$Bus == b, "Island"][1:1])
print(map[b])
}
}
prints a number of lines where periods$Island does not match the corresponding
value in map:
[1] "ALB0331"
[1] SI
Levels: NI SI
ALB0331
NI
Levels: NI SI
[1] "APS0111"
[1] NI
...
Clearly, I've missed the point here. Would anyone be so kind as help me
find it or suggest which FM I might need to R?
Cheers,
Geoff
[1]
http://stackoverflow.com/questions/7547597/dictionary-style-replace-multiple-items-in-r
Hello, Try, after the first instruction but before the second and third, merge(periods, map, by.x="Bus", by.y="node", all.x=TRUE) Also, it's better to use dput() to give data examples. To paste the output of this or similar in a post is the recomended way: dput(head(periods, 20)) # or 30, or enough to be representative Hope this helps, Rui Barradas Em 12-06-2012 03:27, Geoff Leyland escreveu:> Hi, I'm new here, > > I'd like to map a set of values in a data frame to another set of values in another frame (think a c++ map<>, a python dict or a hash lookup) > > Specifically, I have a data frame of information about trading periods in the NZ electricity market. For each period I have information about each bus (or node) in the network. I'd like add a "column" to the data frame containing the island that the bus is on. > > I'm afraid my success at searching for an answer is restricted by not knowing what this operation might be called in R, but I found a something on stackoverflow [1] and tried the following: > > map <- read.table("../node_islands.csv", header=TRUE, sep=",") > map <- setNames(map$island, map$node) > periods$Island = map[periods$Bus] > > Where after the first line, but before the second and third: > >> map[1:3,] > node island > 1 ABY0111 SI > 2 ABY1101 SI > 3 ADD0111 SI > > and: > >> periods[1:3, c("Date", "Period", "Bus", "Price")] > Date Period Bus Price > 1 2004-01-01 1 ABY0111 31.20 > 2 2004-01-01 1 ADD0111 32.43 > 3 2004-01-01 1 ADD0661 32.38 > > This seems to work (it fooled me for quite a while :-) ), but the following check: > > for (b in periods$Bus) > { > if (periods[periods$Bus == b, "Island"] != map[b]) > { > print(b) > print(periods[periods$Bus == b, "Island"][1:1]) > print(map[b]) > } > } > > prints a number of lines where periods$Island does not match the corresponding value in map: > > [1] "ALB0331" > [1] SI > Levels: NI SI > ALB0331 > NI > Levels: NI SI > [1] "APS0111" > [1] NI > ... > > Clearly, I've missed the point here. Would anyone be so kind as help me find it or suggest which FM I might need to R? > > Cheers, > Geoff > > [1] http://stackoverflow.com/questions/7547597/dictionary-style-replace-multiple-items-in-r > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >
Geoff,
I'm not exactly sure what you're trying to do, but if you want to match
up
information in two data frames according to a common column in each (node
in map and Bus in period), then the merge() function might do the trick
for you. Look at the examples in
?merge
Jean
Geoff Leyland <geoff_leyland@fastmail.fm> wrote on 06/11/2012 09:27:39 PM:
> Hi, I'm new here,
>
> I'd like to map a set of values in a data frame to another set of
> values in another frame (think a c++ map<>, a python dict or a hash
lookup)>
> Specifically, I have a data frame of information about trading
> periods in the NZ electricity market. For each period I have
> information about each bus (or node) in the network. I'd like add a
> "column" to the data frame containing the island that the bus is
on.
>
> I'm afraid my success at searching for an answer is restricted by
> not knowing what this operation might be called in R, but I found a
> something on stackoverflow [1] and tried the following:
>
> map <- read.table("../node_islands.csv", header=TRUE,
sep=",")
> map <- setNames(map$island, map$node)
> periods$Island = map[periods$Bus]
>
> Where after the first line, but before the second and third:
>
> > map[1:3,]
> node island
> 1 ABY0111 SI
> 2 ABY1101 SI
> 3 ADD0111 SI
>
> and:
>
> > periods[1:3, c("Date", "Period", "Bus",
"Price")]
> Date Period Bus Price
> 1 2004-01-01 1 ABY0111 31.20
> 2 2004-01-01 1 ADD0111 32.43
> 3 2004-01-01 1 ADD0661 32.38
>
> This seems to work (it fooled me for quite a while :-) ), but the
> following check:
>
> for (b in periods$Bus)
> {
> if (periods[periods$Bus == b, "Island"] != map[b])
> {
> print(b)
> print(periods[periods$Bus == b, "Island"][1:1])
> print(map[b])
> }
> }
>
> prints a number of lines where periods$Island does not match the
> corresponding value in map:
>
> [1] "ALB0331"
> [1] SI
> Levels: NI SI
> ALB0331
> NI
> Levels: NI SI
> [1] "APS0111"
> [1] NI
> ...
>
> Clearly, I've missed the point here. Would anyone be so kind as
> help me find it or suggest which FM I might need to R?
>
> Cheers,
> Geoff
>
> [1] http://stackoverflow.com/questions/7547597/dictionary-style-
> replace-multiple-items-in-r
[[alternative HTML version deleted]]
On 13/06/2012, at 12:35 AM, Rui Barradas wrote:> Hello,...<merge>... On 13/06/2012, at 12:36 AM, Jean V Adams wrote:> Geoff,...<merge>... Thanks Rui and Jean, merge appears to be what I was looking for, and much better than my workaround for loop.