R help - Dec 2011 - sorting a data.frame (df) by a vector (which is not contained in the df) - unexpected behaviour of match and factor

Dear R colleagues,

consider my data.frame named "df" with 3 columns - being level,
prevalence and sensitivity - and 7 rows of data (see dump below).

df <-
structure(list(level = structure(1:7, .Label = c("0", "1",
"10",
"100", "1010", "11", "110"), class =
"factor"), prevalence structure(c(4L,
2L, 3L, 5L, 6L, 1L, 7L), .Label = c("0.488", "0.5",
"0.754",
"0.788", "0.803", "0.887", "0.905"),
class = "factor"), sensitivity structure(c(6L,
1L, 5L, 4L, 3L, 2L, 1L), .Label = c("0", "0.05",
"0.091", "0.123",
"0.327", "0.933"), class = "factor")), .Names =
c("level", "prevalence",
"sensitivity"), class = "data.frame", row.names = c(NA,
-7L))

I'd like to order df by a vector which is NOT contained in the
data.frame. Let's call this vector desiredOrder (see dump below).

desiredOrder <- c("0", "1", "10",
"100", "11", "110", "1010")

So after sorting, the order of the level column (df$level) should be in
the order of the vector desiredOrder (as well a the associated data in
the other columns).
I know that this is not an easy task to achieve by order(...) as the
order of desiredOrder isn't a natural one. But I would expect both of
the following to work:

## using match
df[match(df$level,desiredOrder),]

## using factor
df[factor(df$level,levels=desiredOrder),]

Unfortunately the result isn't what I expected: I get a data.frame with
the level column in the order 0,1,10,100,110,1010,11 instead of the
order in desiredOrder (0,1,10,100,11,110,1010).

Does anybody see, what I am doing wrong?
I'd appreciate any kind of help very much!
Best regards, Felix

Your desiredOrder vector is a vector of strings. Convert it to numeric and it
should work.
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drflxms <drflxms at googlemail.com> wrote:
>Dear R colleagues,
>
>consider my data.frame named "df" with 3 columns - being level,
>prevalence and sensitivity - and 7 rows of data (see dump below).
>
>df <-
>structure(list(level = structure(1:7, .Label = c("0",
"1", "10",
>"100", "1010", "11", "110"), class =
"factor"), prevalence >structure(c(4L,
>2L, 3L, 5L, 6L, 1L, 7L), .Label = c("0.488", "0.5",
"0.754",
>"0.788", "0.803", "0.887", "0.905"),
class = "factor"), sensitivity >structure(c(6L,
>1L, 5L, 4L, 3L, 2L, 1L), .Label = c("0", "0.05",
"0.091", "0.123",
>"0.327", "0.933"), class = "factor")), .Names
= c("level",
>"prevalence",
>"sensitivity"), class = "data.frame", row.names = c(NA,
-7L))
>
>I'd like to order df by a vector which is NOT contained in the
>data.frame. Let's call this vector desiredOrder (see dump below).
>
>desiredOrder <- c("0", "1", "10",
"100", "11", "110", "1010")
>
>So after sorting, the order of the level column (df$level) should be in
>the order of the vector desiredOrder (as well a the associated data in
>the other columns).
>I know that this is not an easy task to achieve by order(...) as the
>order of desiredOrder isn't a natural one. But I would expect both of
>the following to work:
>
>## using match
>df[match(df$level,desiredOrder),]
>
>## using factor
>df[factor(df$level,levels=desiredOrder),]
>
>Unfortunately the result isn't what I expected: I get a data.frame with
>the level column in the order 0,1,10,100,110,1010,11 instead of the
>order in desiredOrder (0,1,10,100,11,110,1010).
>
>Does anybody see, what I am doing wrong?
>I'd appreciate any kind of help very much!
>Best regards, Felix
>
>______________________________________________
>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.

drflxms wrote
> 
> Dear R colleagues,
> 
> consider my data.frame named "df" with 3 columns - being level,
> prevalence and sensitivity - and 7 rows of data (see dump below).
> 
> df <-
> structure(list(level = structure(1:7, .Label = c("0",
"1", "10",
> "100", "1010", "11", "110"), class
= "factor"), prevalence > structure(c(4L,
> 2L, 3L, 5L, 6L, 1L, 7L), .Label = c("0.488", "0.5",
"0.754",
> "0.788", "0.803", "0.887",
"0.905"), class = "factor"), sensitivity >
structure(c(6L,
> 1L, 5L, 4L, 3L, 2L, 1L), .Label = c("0", "0.05",
"0.091", "0.123",
> "0.327", "0.933"), class = "factor")), .Names
= c("level", "prevalence",
> "sensitivity"), class = "data.frame", row.names = c(NA,
-7L))
> 
> I'd like to order df by a vector which is NOT contained in the
> data.frame. Let's call this vector desiredOrder (see dump below).
> 
> desiredOrder <- c("0", "1", "10",
"100", "11", "110", "1010")
> 
> So after sorting, the order of the level column (df$level) should be in
> the order of the vector desiredOrder (as well a the associated data in
> the other columns).
> I know that this is not an easy task to achieve by order(...) as the
> order of desiredOrder isn't a natural one. But I would expect both of
> the following to work:
> 
> ## using match
> df[match(df$level,desiredOrder),]
> 
> ## using factor
> df[factor(df$level,levels=desiredOrder),]
> 
> Unfortunately the result isn't what I expected: I get a data.frame with
> the level column in the order 0,1,10,100,110,1010,11 instead of the
> order in desiredOrder (0,1,10,100,11,110,1010).
> 
> Does anybody see, what I am doing wrong?
> 
Try this:

df[match(desiredOrder,df$level),]

Berend


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