[R] plot custom x axis ticks values

[e-letter]

On 15/02/2013, Duncan Murdoch <murdoch.duncan at gmail.com> wrote:
> On 13-02-15 3:28 AM, e-letter wrote:
>> On 15/02/2013, Jim Lemon <jim at bitwrit.com.au> wrote:
>>> On 02/14/2013 09:41 PM, e-letter wrote:
>>>> Readers,
>>>>
>>>> For this data set:
>>>>
>>>> testvalues<-c(10,20,30,40)
>>>>
>>>> How to amend the plot instruction:
>>>>
>>>> plot(testvalues,ann=FALSE,type='l',yaxt='n',xaxt='n')
>>>>
>>>> so that x axis ticks labels can be added to existing graph with
>>>> arbitrary value such as 0,100,200,300)?
>>>>
>>> Hi r2151,
>>> If you want the labels to fit on the axis you will have to include this
>>> information in the call to "plot":
>>>
>>> plot(testvalues,ann=FALSE,type='l',yaxt='n',xaxt='n',ylim=c(0,300))
>>> axis(2,at=c(0,100,200,300))
>>>
>>
>> plot(testvalues,ann=FALSE,type='l',yaxt='n',xaxt='n',xlim=c(0,300))
>> axis(1,at=c(0,100,200,300))
>>
>> The use of 'xlim' makes the graph unacceptable. Instead, it would be
>> better to plot:
>>
>> plot(testvalues,ann=FALSE,type='l',yaxt='n')
>>
>> The x-axis shows tick marks '1.0', '1.5', ...
>>
>> It is required to replace these values with custom values (e.g. 10, 20...
>> etc.)
>
> Why not rescale the values before plotting, and use the automatic ticks?
>   You can lie about the user scale, but it doesn't always give a helpful
> plot, e.g.
>
> axis(1, at=1:4, labels=c(100, 300, 400, 200))
>

Tried, but realised that this works when the vectors for 'at' and
'labels' are equal size. For a data set of e.g. 10 values, syntax
error returns.