R help - Nov 2009 - One basic question - combining two conditions

Dear R helpers

Suppose I want to use two conditions

if (x >= 42) and (x<48)

z = 45

else 

if (x>= 48) and (x<60)

z = 14

how do use this "and" operator to combine two conditions.

I am sorry as I know for many of you, this is very basic question but I am new
to R and trying to learn it as early as possible.

Extremely sorry for this stupid question.


Please guide

Julia
************************************************



Only a man of Worth sees Worth in other men



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On Tue, 17 Nov 2009 00:26:13 -0800 (PST) Julia Cains 
<julia_cains at yahoo.com> wrote:
> how do use this "and" operator to combine two conditions.
> 
> I am sorry as I know for many of you, this is very basic question 
> but I am new to R and trying to learn it as early as possible.
The 'and' operator is called '&' in R. Try

?'&'

to display the help page.

You might also be interested in

?ifelse
and
?"if"

-- 
Karl Ove Hufthammer

Julia Cains wrote:
> Dear R helpers
> 
> Suppose I want to use two conditions
> 
> if (x >= 42) and (x<48)
> 
> z = 45
> 
> else 
> 
> if (x>= 48) and (x<60)
> 
> z = 14
> 
> how do use this "and" operator to combine two conditions.
> 
> I am sorry as I know for many of you, this is very basic question but I am
new to R and trying to learn it as early as possible.
> 
> Extremely sorry for this stupid question.
Have a look at help(Logic).



-- 
   O__  ---- Peter Dalgaard             ?ster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark      Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)              FAX: (+45) 35327907

On 17-Nov-09 08:26:13, Julia Cains wrote:
> Dear R helpers
> Suppose I want to use two conditions
> 
> if (x >= 42) and (x<48)
> 
> z = 45
> 
> else 
> 
> if (x>= 48) and (x<60)
> 
> z = 14
> 
> how do use this "and" operator to combine two conditions.
> 
> I am sorry as I know for many of you, this is very basic question
> but I am new to R and trying to learn it as early as possible.
> 
> Extremely sorry for this stupid question.
> Please guide
> Julia
> ************************************************
You can do it by using "&" to express "and". But also be
careful
how you lay out an "if ... else ...":

  if (x >= 42) & (x<48) { z = 45 } else 
  if (x >= 48) & (x<60) z = 14

See ?"&" [note the quotes] for general information on the logical
operators, and see ?Control for information about if, if .. else,
and so on.

The point about the layout of "if ... else ..." is that the first
line of

  if (x >= 42) & (x<48) { z = 45 }
  else if (x >= 48) & (x<60) z = 14

is a complete statement, so will be evaluated without looking
any further. Therefore the second line will be interpreted as
a syntax error, since a stand-alone statement cannot begin
with "else" ("else" needs a matching "if"
preceding it; but
that has already been swallowed because the first line was
a complete statement). Putting the "else" in the same line
as the "if" means that R knows it is there before executing
the "if".

Ted.

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E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk>
Fax-to-email: +44 (0)870 094 0861
Date: 17-Nov-09                                       Time: 09:15:11
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