Dana Sevak wrote:
Dear R Helpers,
I have trouble applying reShape and reshape although I read the documentation
and several posts, so I would very much appreciate your help on the two points
below.
I have a dataframe
df = data.frame(Name=c("a", "a", "a", "b", "b", "c"), X1=c("12", "13", "14", "20", "25",
"30"), X2 = c(200, 250, 300, 600, 700, 4))
df
Name X1 X2
1 a 12 200
2 a 13 250
3 a 14 300
4 b 20 600
5 b 25 700
6 c 30 900
First I need to add an additional column to this dataframe that will count the
number of rows per each Name entry. The resulting df should look like:
df.index = data.frame(Name=c("a", "a", "a", "b", "b", "c"), X1=c(12, 13, 14,
20, 25, 30), X2 = c(200, 250, 300, 600, 700, 4), Index=c(1,2,3,1,2,1))
df.index
Name X1 X2 Index
1 a 12 200 1
2 a 13 250 2
3 a 14 300 3
4 b 20 600 1
5 b 25 700 2
6 c 30 900 1
How can I do this?
Secondly, I would like to reshape this dataframe in the form:
df2
1 2 3
a 12 13 14
b 20 25 NA
c 30 NA NA
This does it more or less your way:
ds <- split(df, df$Name)
ds <- lapply(ds, function(x){x$Index <- seq_along(x[,1]); x})
df2 <- unsplit(ds, df$Name)
tapply(df2$X1, df2[,c("Name", "Index")], function(x) x)
athough there may exist much easier ways ...
Uwe Ligges
Since the df is sorted by Name and X2, I would need that the available X1
values populate the resulting rows in df2 from left to right (i.e. if only one
value is available, it is written in the first column and the remaining columns
get NAs). If I could generate the Index column, I think I could accomplish
this with:
df2 = reShape(df.index$X1, id=df.index$Name, colvar=df.index$Index)
colnames(df2) = c("V1", "V2", "V3")
However, is there a way to get to df2 without using the Index column and still
have the NAs written as described above?
Thank you so much for your help on these two issues.
With best regards,
Dana Sevak
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