[R] IF/Else

[Gabor Grothendieck]

Try using switch:

bioden <- Biomass /
  switch(paste(Gear),
    `20` = 141,
    `23` = 68,
    # ... fill in the ones I have omitted ...,
    `301` = DIST_TOW*4*1853)


On 11/10/05, Guenther, Cameron <Cameron.Guenther at myfwc.com> wrote:
> Hi,
> I am trying to write a for loop with if else statements to calculate
> biomass density estimates for different types of sampling gear.
> My code is:
>
> bmd=for (i in 1:length(Gear)){
> if (Gear==20) {bioden=Biomass/141}
> else {if (Gear==23) {bioden=Biomass/68}}
> else {if (Gear==160) {bioden=Biomass/4120}}
> else {if (Gear==170) {bioden=Biomass/2210}}
> else {if (Gear==300) {bioden=Biomass/(DIST_TOW*4*1853)}}
> else {if (Gear==301) {bioden=Biomass/(DIST_TOW*4*1853)}}
> }
>
> The syntax that is returned is:
>
> > bmd=for (i in 1:length(Gear)){
> + if (Gear==20) {bioden=Biomass/141}
> + else {if (Gear==23) {bioden=Biomass/68}}
> + else {if (Gear==160) {bioden=Biomass/4120}}
> Error: syntax error in:
> "else {if (Gear==23) {bioden=Biomass/68}}
> else"
> > else {if (Gear==170) {bioden=Biomass/2210}}
> Error: syntax error in "else"
> > else {if (Gear==300) {bioden=Biomass/(DIST_TOW*4*1853)}}
> Error: syntax error in "else"
> > else {if (Gear==301) {bioden=Biomass/(DIST_TOW*4*1853)}}
> Error: syntax error in "else"
> > }
> Error: syntax error in "}"
>
> It appears that the code works for the first two if/else statements and
> then fails there after.  Any suggestions?
>
> Cameron Guenther
> Associate Research Scientist
> FWC/FWRI, Marine Fisheries Research
> 100 8th Avenue S.E.
> St. Petersburg, FL 33701
> (727)896-8626 Ext. 4305
> cameron.guenther at myfwc.com
>
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