[Rd] sum() vs cumsum() implicit type coercion

[Tomas Kalibera]

On 8/23/20 5:02 PM, Rory Winston wrote:
> Hi
>
> I noticed a small inconsistency when using sum() vs cumsum()
>
>   I have a char-based series
>
>   > tryjpy$long
>
>   [1] "0.0022"  "-0.0002" "-0.0149" "-0.0023" "-0.0342" "-0.0245" "-0.0022"
>
>   [8] "0.0003"  "-0.0001" "-0.0004" "-0.0036" "-0.001"  "-0.0011" "-0.0012"
>
> [15] "-0.0006" "0.0016"  "0.0006"
>
> When I run sum() vs cumsum() , sum fails but cumsum converts the
> series to numeric before summing:
>
>> sum(tryjpy$long)
> Error in sum(tryjpy$long) : invalid 'type' (character) of argument
>
>> cumsum(tryjpy$long)
>   [1]  0.0022  0.0020 -0.0129 -0.0152 -0.0494 -0.0739 -0.0761 -0.0758 -0.0759
> [10] -0.0763 -0.0799 -0.0809 -0.0820 -0.0832 -0.0838 -0.0822 -0.0816
>
> Which I guess is due to the following line in do_cum():
>
> PROTECT(t = coerceVector(CAR(args), REALSXP));
> This might be fine and there may be very good reasons why there is no
> coercion in sum - just seems a little inconsistent in usage

Yes. I don't know the reason for this design, but please note it is 
documented in ?sum and in ?cumsum, which would also make it harder to 
change. One can always use a consistent subset (not rely on the coercion 
e.g. from characters).

Best
Tomas

>
> Cheers
> -- Rory
>
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