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Help with loop

4 messages · paulalou, Rui Barradas, Charles Stangor +1 more

paulalou
# 
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. Then the missing data in df1$colb to be replaced with the
corresponding value in df2$colb etc.

I can get this to work column by column with single input lines but as my
original dataset is a lot larger I'm wanting a create a loop but can't work
out how.

The single line command is:

 df1$cola[is.na(df1$cola)]<-df2$cola

I've tried a replace function within a loop but get error messages:

list<-colnames(df1)

for (i in list) {
 r<-replace(df1$i,df1$i[is.na(df1$i)],df2$i)
 }


with error messages of:

Warning messages:
1: In is.na(mymat$snp) :
  is.na() applied to non-(list or vector) of type 'NULL'

Can anyone help me with this?

Thanks 

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Rui Barradas
# 
Hello,

A one-liner could be


df1 <- read.table(text="
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
", header=TRUE)

df2 <- read.table(text="
cola colb colc cold cole
1  1.4  0.8 0.02  1.6  0.6
", header=TRUE)

sapply(names(df1), function(nm) {df1[[nm]][is.na(df1[[nm]])] <- 
df2[[nm]]; df1[[nm]]})


Avoid loops, use *apply.

Hope this helps,

Rui Barradas

Em 11-07-2012 15:11, paulalou escreveu:
arun
# 
Hi,

Try this:

func1<-function(x,y,z)
?{ifelse(is.na(y[[x]]),z[[x]],y[[x]])}
dat3<-data.frame(lapply(colnames(df1),function(x) func1(x,df1,df2)))
colnames(dat3)<-colnames(df1)
dat3
? cola colb? colc cold cole
1? 1.4? 5.0? 9.00? 1.6 17.0
2? 1.4? 6.0? 0.02 14.0? 0.6
3? 3.0? 0.8 11.00 15.0 19.0
4? 4.0? 8.0 12.00? 1.6 20.0
#or
sapply(colnames(df1),function(x) func1(x,df1,df2))

A.K.



----- Original Message -----
From: paulalou <pls28 at medschl.cam.ac.uk>
To: r-help at r-project.org
Cc: 
Sent: Wednesday, July 11, 2012 10:11 AM
Subject: [R] 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. Then the missing data in df1$colb to be replaced with the
corresponding value in df2$colb etc.

I can get this to work column by column with single input lines but as my
original dataset is a lot larger I'm wanting a create a loop but can't work
out how.

The single line command is:

df1$cola[is.na(df1$cola)]<-df2$cola

I've tried a replace function within a loop but get error messages:

list<-colnames(df1)

for (i in list) {
r<-replace(df1$i,df1$i[is.na(df1$i)],df2$i)
}


with error messages of:

Warning messages:
1: In is.na(mymat$snp) :
? is.na() applied to non-(list or vector) of type 'NULL'

Can anyone help me with this?

Thanks 

--
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