Returns 0.0 if flavour PIDs is not part of the Grid

CHANGELOG.md

@@ -36,6 +36,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- Return zero if PID is not in the Grid (https://github.com/QCDLab/neopdf/pull/78).
+- Changed the passing of the name of the PDF as a positional argument in the
+  CLI (https://github.com/QCDLab/neopdf/pull/78).
 - Move the computation of the logarithmic transformation out of the interpolation.
 - Modified `GridArray::find_subgrid` to accept more combinations of variables
   so that the construction of subgrids is generic.

docs/cli-tutorials.md

@@ -25,7 +25,7 @@ feature.
 To read the metadata for a given PDF set:
 
 ```bash
-neopdf read metadata --pdf-name NNPDF40_nnlo_as_01180
+neopdf read metadata NNPDF40_nnlo_as_01180
 ```
 
 - `--pdf-name`: Name of the PDF set (can be a `NeoPDF` or `LHAPDF` set).
@@ -54,7 +54,7 @@ Interpolator Type: LogBicubic
 To get the number of subgrids a PDF contains:
 
 ```bash
-neopdf read num_subgrids --pdf-name NNPDF40_nnlo_as_01180
+neopdf read num_subgrids NNPDF40_nnlo_as_01180
 ```
 
 - `--pdf-name`: Name of the PDF set.
@@ -64,7 +64,7 @@ neopdf read num_subgrids --pdf-name NNPDF40_nnlo_as_01180
 To get the knot values for a given subgrid:
 
 ```bash
-neopdf read subgrid-info --pdf-name NNPDF40_nnlo_as_01180 --member=0 --subgrid-index=1
+neopdf read subgrid-info NNPDF40_nnlo_as_01180 --member=0 --subgrid-index=1
 ```
 
 - `--pdf-name`: Name of the PDF set.
@@ -109,7 +109,7 @@ neopdf write metadata --path NNPDF40_nnlo_as_01180.neopdf.lz4 --key SetType --va
 To compute the interpolated function $xf(x, Q^2)$ for a given PDF set, member, and flavor:
 
 ```bash
-neopdf compute xfx_q2 --pdf-name NNPDF40_nnlo_as_01180 --member=0 --pid=21 1e-3 10.0
+neopdf compute xfx_q2 NNPDF40_nnlo_as_01180 --member=0 --pid=21 1e-3 10.0
 ```
 
 - `--pdf-name`: Name of the PDF set (can be a `NeoPDF` or `LHAPDF` set).
@@ -131,7 +131,7 @@ neopdf compute xfx_q2 --pdf-name NNPDF40_nnlo_as_01180 --member=0 --pid=21 1e-3
 To compute the strong coupling constant $\alpha_s(Q^2)$ for a given PDF set and member:
 
 ```bash
-neopdf compute alphas_q2 --pdf-name NNPDF40_nnlo_as_01180 --member=0 --q2=10
+neopdf compute alphas_q2 NNPDF40_nnlo_as_01180 --member=0 --q2=10
 ```
 
 - `--q2`: The $Q^2$ value at which to evaluate $\alpha_s$.
@@ -145,7 +145,7 @@ neopdf compute alphas_q2 --pdf-name NNPDF40_nnlo_as_01180 --member=0 --q2=10
 To convert a standard LHAPDF set into the new, compressed `NeoPDF` format:
 
 ```bash
-neopdf write convert --pdf-name NNPDF40_nnlo_as_01180 --output NNPDF40_nnlo_as_01180.neopdf.lz4
+neopdf write convert NNPDF40_nnlo_as_01180 --output NNPDF40_nnlo_as_01180.neopdf.lz4
 ```
 
 - `--output`: The output file name for the `NeoPDF` grid (should end with `.neopdf.lz4`).
@@ -197,7 +197,7 @@ This will generate a `nNNPDF30_nlo_as_0118.neopdf.lz4` PDF grid that also contai
 dependence. One can now check the value of $xf(A, x, Q^2)$ for the Iron $^{56}_{26}\mathrm{Fe}$:
 
 ```bash
-neopdf compute xfx_q2 --pdf-name nNNPDF30_nlo_as_0118.neopdf.lz4 --member=0 --pid=21 56 1e-3 10.0
+neopdf compute xfx_q2 nNNPDF30_nlo_as_0118.neopdf.lz4 --member=0 --pid=21 56 1e-3 10.0
 ```
 
 ### Combine multiple  $\alpha_s$ LHAPDF sets
@@ -225,7 +225,7 @@ Note that the names of the PDF sets can be passed via the command line using the
 `--pdf--name`. We can then interpolate the $\alpha_s = 0.1180$ value:
 
 ```bash
-neopdf compute xfx_q2 --pdf-name NNPDF40_nnlo.neopdf.lz4 --member=0 --pid=21 0.1180 1e-3 10.0
+neopdf compute xfx_q2 NNPDF40_nnlo.neopdf.lz4 --member=0 --pid=21 0.1180 1e-3 10.0
 ```
 
 !!! danger "Warning"
@@ -257,15 +257,15 @@ multiple subgrids (as we have seen before using the `subgrid-info` command), it
 first how many subgrids a given set member contains.
 
 ```bash
-> neopdf read num_subgrids --pdf-name NNPDF40_nnlo_as_01180.neopdf.lz4
+> neopdf read num_subgrids NNPDF40_nnlo_as_01180.neopdf.lz4
 
 2
 ```
 
 We can look at the contents of the first subgrid for the **gluon** PDF:
 
 ```bash
-> neopdf read subgrid --pdf-name NNPDF40_nnlo_as_01180.neopdf.lz4 --member=0 --subgrid-index=0 --pid=21
+> neopdf read subgrid NNPDF40_nnlo_as_01180.neopdf.lz4 --member=0 --subgrid-index=0 --pid=21
 
   [x | Q2]   2.72250e0   3.19494e0   3.77488e0   4.49175e0   5.38430e0   6.50400e0   7.91974e0
 1.00000e-9  1.48441e-1  -1.47266e0  -3.42816e0  -5.57841e0  -7.73893e0  -9.65268e0  -1.10375e1

neopdf/src/gridpdf.rs

@@ -287,10 +287,10 @@ impl GridPDF {
             Error::SubgridNotFound { x, q2 }
         })?;
 
-        let pid_idx = self
-            .knot_array
-            .pid_index(flavor_id)
-            .ok_or_else(|| Error::InterpolationError(format!("Invalid flavor ID: {flavor_id}")))?;
+        let pid_idx = match self.knot_array.pid_index(flavor_id) {
+            Some(idx) => idx,
+            None => return Ok(0.0),
+        };
 
         let use_log = matches!(
             self.info.interpolator_type,
@@ -353,10 +353,10 @@ impl GridPDF {
             return Ok(Vec::new());
         }
 
-        let pid_idx = self
-            .knot_array
-            .pid_index(flavor_id)
-            .ok_or_else(|| Error::InterpolationError(format!("Invalid flavor ID: {flavor_id}")))?;
+        let pid_idx = match self.knot_array.pid_index(flavor_id) {
+            Some(idx) => idx,
+            None => return Ok(vec![0.0; points.len()]),
+        };
 
         if !matches!(self.info.interpolator_type, InterpolatorType::LogChebyshev) {
             return Err(Error::InterpolationError(