Displaying 20 results from an estimated 5000 matches similar to: "Infinite degrees of freedom for F-distribution"
2005 May 09
4
Error in F test on version 2.1.0
Hi,
I make a upgrade to R 2.1.0 and in some analysis I give an error:
anova(model,test="F")
Analysis of Deviance Table
Model: binomial, link: logit
Response: landing/total
Terms added sequentially (first to last)
Df Deviance Resid. Df Resid. Dev F Pr(>F)
NULL 16 105.079
trat 1 93.149 15 11.930 93.15
Warning message:
2005 Jul 11
4
exact values for p-values - more information.
Hi there,
If I do an lm, I get p-vlues as
p-value: < 2.2e-16
This is obtained from F =39540 with df1 = 1, df2 = 7025.
Suppose am interested in exact value such as
p-value = 1.6e-16 (note = and not <)
How do I go about it?
stephen
2005 Jan 21
2
chi-Squared distribution in Friedman test
Dear R helpers:
Thanks for the previous reply. I am using Friedman racing test. According the the book "Pratical Nonprametric Statistic" by WJ Conover, after computing the statistics, he suggested to use chi-squared or F distribution to accept or reject null hypothesis. After looking into the source code, I found that R uses chi-sqaured distribution as below:
PVAL <-
2008 Jun 05
2
qf with infinite df
Dear all,
I found the following behaviour
> rf(5,Inf,Inf)
[1] 1 1 1 1 1
but
> qf(0.1,Inf,Inf)
[1] NaN
Warning messages:
1: In qf(0.1, Inf, Inf) : value out of range in 'lgamma'
2: In qf(p, df1, df2, lower.tail, log.p) : NaNs produced
incidentally,
> pf(1.00000000000001,Inf,Inf)
[1] 1
> pf(1.0000000000000001,Inf,Inf)
[1] 0.5
Is this the expected behaviour?
Thanks
2007 Feb 20
1
Mahalanobis distance and probability of group membership using Hotelling's T2 distribution
I want to calculate the probability that a group will include a particular
point using the squared Mahalanobis distance to the centroid. I understand
that the squared Mahalanobis distance is distributed as chi-squared but that
for a small number of random samples from a multivariate normal population
the Hotellings T2 (T squared) distribution should be used.
I cannot find a function for
2008 Sep 14
5
difference of two data frames
Hello
I have 2 data frames DF1 and DF2 where DF2 is a subset of DF1:
DF1= data.frame(V1=1:6, V2= letters[1:6])
DF2= data.frame(V1=1:3, V2= letters[1:3])
How do I create a new data frame of the difference between DF1 and DF2
newDF=data.frame(V1=4:6, V2= letters[4:6])
In my real data, the rows are not in order as in the example I provided.
Thanks much
Joseph
[[alternative HTML version
2013 Feb 26
2
merging or joining 2 dataframes: merge, rbind.fill, etc.?
#I want to "merge" or "join" 2 dataframes (df1 & df2) into a 3rd
(mydf). I want the 3rd dataframe to contain 1 row for each row in df1
& df2, and all the columns in both df1 & df2. The solution should
"work" even if the 2 dataframes are identical, and even if the 2
dataframes do not have the same column names. The rbind.fill function
seems to work. For
2011 Aug 18
2
Best way/practice to create a new data frame from two given ones with last column computed from the two data frames?
Dear expeRts,
What is the best approach to create a third data frame from two given ones, when
the new/third data frame has last column computed from the last columns of the two given
data frames?
## Okay, sounds complicated, so here is an example. Assume we have the two data frames:
df1 <- data.frame(Year=rep(2001:2010, each=2), Group=c("Group 1","Group 2"), Value=1:20)
2012 Jul 11
4
Help with loop
Hi,
I have two dataframes:
The first, df1, contains some missing data:
cola colb colc cold cole
1 NA 5 9 NA 17
2 NA 6 NA 14 NA
3 3 NA 11 15 19
4 4 8 12 NA 20
The second, df2, contains the following:
cola colb colc cold cole
1 1.4 0.8 0.02 1.6 0.6
I'm wanting all missing data in df1$cola to be replaced by the value of
df2$cola.
2013 Jan 02
2
rbind: inconsistent behaviour with empty data frames?
The rbind on empty and nonempty data frames behaves inconsistently. I am
not sure if by design.
In the first example, first row is deleted, which may or may not be on
purpose:
df1 <- data.frame()
df2 <- data.frame(foo=c(1, 2), bar=c("a", "b"))
rbind(df1, df2)
foo bar
2 2 b
Now if we continue:
df1 <- data.frame(matrix(0, 0, 2))
names(df1) <- names(df2)
2009 Jan 21
3
merging several dataframes from a list
Hi there,
I have a list of dataframes (generated by reading multiple files) and all
dataframes are comparable in dimension and column names. They also have a
common column, which, I'd like to use for merging. To give a simple example of
what I have:
df1 <- data.frame(c(LETTERS[1:5]), c(2,6,3,1,9))
names(df1) <- c("pos", "data")
df3 <- df2 <- df1
df2$data
2008 Feb 10
11
data frame question
Hello
I have 2 data frames df1 and df2. I would like to create a
new data frame new_df which will contain only the common rows based on the first 2
columns (chrN and start). The column score in the new data frame
should
be replaced with a column containing the average score (average_score) from df1
and df2.
df1= data.frame(chrN= c(“chr1”, “chr1”, “chr1”, “chr1”, “chr2”,
“chr2”, “chr2”),
2012 Sep 27
4
Colsplit, removing parts of a string
Hi,
I am using colsplit (package = reshape) to split all strings
in a column according to the same patterns. Here
an example:
library(reshape2)
df1 <- data.frame(x=c("str1_name2", "str3_name5"))
df2 <- data.frame(df1, colsplit(df1$x, pattern = "_", names=c("str","name")))
This is nearly what I want but I want to remove the words
2010 Dec 16
2
Compare two dataframes
Hello,
I have two dataframes DF1 and DF2 that should be identical but are not
(DF1 has some rows that aren't in DF2, and vice versa). I would like
to produce a new dataframe DF3 containing rows in DF1 that aren't in
DF2 (and similarly DF4 would contain rows in DF2 that aren't in DF1).
I have a solution for this problem (see self contained example below)
but it's awkward and
2011 Apr 30
3
indexing into a data.frame using another data.frame that also contains values for replacement
Hello all,
I have a quandry I have been scratching my head about for a
while. I've searched the manual and the web and have not been able to
find an acceptable result, so I am hoping for some help.
I have two data frames and I want to index into the first using
the second, and replace the specific values I have indexed with more
values from the second data.frame. I can do this
2012 Aug 14
4
Subsetting rows by multiple levels of selected values
Dear list,
Let's say we have a data frame as follows,
>expand.grid(a=1:5,b=c(1,5,10,20),DV=c(0.1,0.2,0.3))->df1
>df1$DV<-rgamma(60,shape=10)
columns a and b are two levels. DV is the column with values we are
interested in.
Then another data frame df2 with values as follows
data.frame(a=c(2,2,3,4,5),b=c(5,10,1,5,20))->df2
Now I want to a subset of df1 that match df2 at the
2010 Nov 05
4
assignment operator saving factor level as number
Hi all,
I have a dataframe (df1) that I am trying to select values from to a second
dataframe that at the current time is only for the selected items from df1
(df2). The values that I am trying to save from df1 are factors with
alphanumeric names
df1 looks like this:
'data.frame': 3014 obs. of 13 variables:
$ Num : int 1 1 1 2 2 2 3 3 3 4 ...
$ Tag_Num : int 1195
2012 Jun 03
2
merging single column from different dataframe
Hi all,
probably really simple to solve, but having no background in programming I
haven't been able to figure this out: I have two dataframes like
df1 <- data.frame(names1=c('aa','ab', 'ac', 'ad'), var1=c(1,5,7,12))
df2 <- data.frame(names2=c('aa', 'ab', 'ac', 'ad', 'ae'),
var2=c(3,6,9,12,15))
Now I want merge
2017 Oct 10
1
About multiple panels with limited space in-between
Hi R users,
I have a question about plotting. The following two datasets are an
example. What I have in mind is like the attached figure, but just have two
rows, top row is for DF1, bottom row is for DF2. The top and bottom rows,
have x-axis as var1, var2, var3, etc, while the y-axis represents A. For
each row, only the leftmost panel has y-axis ticks and label. For the two
rows, only the bottom
2009 Mar 22
5
If statement generates two outputs
Hi,
How do I tell an if statement to generate two seperate outputs.
E.g If X>5 I want to create df1 and df2:
if (X>5) {df1<-c(4,5,6,7,8) AND df2<-c(9,10,11,12,13)}
Thanks,
James
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