calculate_param accepting ifelse statement for ppi but not scan

[adokter]

# start a tempfile
tempfile=tempfile("KBGM_example")
# Download a NEXRAD file and save as KBGM_example
download.file(
    "https://noaa-nexrad-level2.s3.amazonaws.com/2019/10/01/KBGM/KBGM20191001_000542_V06",
    method="libcurl", mode="wb", tempfile
)
# Calculate MistNet segmentation
mistnet_pvol <- apply_mistnet(tempfile)
# Replace DBZH values with NA when CELL >=1
# produces an error:
calculate_param(mistnet_pvol$scans[[1]], DBZH = ifelse(CELL >=1, NA, DBZH))

Last statement produces:

Error in Ops.param(test) : argument "e2" is missing, with no default

If we convert the scan to a ppi, the operation does succeed:

# convert scan to ppi:
my_ppi <- project_as_ppi(mistnet_pvol$scans[[1]])
# Replace DBZH values with NA when CELL >=1
# Succeeds where operations failed earlier for scan:
calculate_param(my_ppi, DBZH = ifelse(CELL >=1, NA, DBZH))

@bart1 as the original author of calculate_param() would you be able to generalize this to work also on scan and pvol objects? Brushing out weather like this is quite a common operation people want to use, so would be great if we can support it. If not, we need a more informative error message for why this isn't possible.

[bart1]

I quickly checked, the first problem is that ifelse is not vectored contrasting to if_else from dplyr, here are some examples:

require(bioRad)
#> Loading required package: bioRad
#> Welcome to bioRad version 0.7.3.9000
#> Attempting to load MistNet from: /home/bart/R/x86_64-pc-linux-gnu-library/4.4/vol2birdR/lib 
#> MistNet successfully initialized.
#> using vol2birdR version 1.0.2 (MistNet installed)
require(dplyr)
#> Loading required package: dplyr
#> ...
#>     intersect, setdiff, setequal, union
tempfile=tempfile("KBGM_example")
download.file(
  "https://noaa-nexrad-level2.s3.amazonaws.com/2019/10/01/KBGM/KBGM20191001_000542_V06",
  method="libcurl", mode="wb", tempfile
)
mistnet_pvol <- apply_mistnet(tempfile)
#> Checking file before processing: /tmp/RtmpcW1oyE/KBGM_examplef9d6935579c 
#> ...
#> Running MistNet...done
calculate_param(get_scan(mistnet_pvol,0),
                DBZH = if_else(c(CELL) >=1, NA, c(DBZH)))
#>                   Polar scan (class scan)
#> 
#>      parameters:  DBZH VRADH RHOHV WRADH WEATHER BACKGROUND CELL PHIDP BIOLOGY ZDR 
#> elevation angle:  0.483395 deg
#>            dims:  1201 bins x 720 rays
calculate_param(mistnet_pvol, 
                DBZH = if_else(c(CELL) >=1, NA, c(DBZH)))
#>                Polar volume (class pvol)
#> 
#>      # scans:  9 
#>        radar:  KBGM 
#>       source:  RAD:KBGM,PLC:BINGHAMTON,state:NY,radar_name:KBGM 
#> nominal time:  2019-10-01 00:05:42
calculate_param(get_scan(mistnet_pvol,0),
                DBZH = dplyr::if_else(c(CELL) >=1, NA, c(DBZH)))
#> Error in if (as.character(as.list(substitute(...))[[1L]]) == "list") {: the condition has length > 1

The later error is one I need to fix. I guess for the other problem it might be mostly important to clarify the documentation and explain why c and if_else is needed.

^{Created on 2024-09-13 with reprex v2.1.0}

[bart1]

I will make a pull request later