Jungfraujoch/image_analysis/LoadFCalcFromMtz.cpp

// SPDX-FileCopyrightText: 2025 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
// SPDX-License-Identifier: GPL-3.0-only

#include "LoadFCalcFromMtz.h"

#include <cmath>
#include <cstdint>
#include <string>
#include <vector>

#include <gemmi/mtz.hpp>

#include "../common/Reflection.h"

std::vector<MergedReflection> LoadFCalcFromMtz(const std::string& path) {
    gemmi::Mtz mtz;
    mtz.read_file_gz(path, true);

    const gemmi::Mtz::Column* fc = mtz.column_with_label("F-model", nullptr, 'F');
    if (fc == nullptr)
        throw std::runtime_error("MTZ does not contain F-model column");

    std::vector<MergedReflection> result;
    result.reserve(static_cast<std::size_t>(mtz.nreflections));

    const std::size_t stride = mtz.columns.size();

    for (int i = 0; i < mtz.nreflections; ++i) {
        const std::size_t row = static_cast<std::size_t>(i) * stride;
        const float f = (*fc)[static_cast<std::size_t>(i)];

        if (std::isnan(f))
            continue;

        MergedReflection r;
        r.h = static_cast<int32_t>(mtz.data[row + 0]);
        r.k = static_cast<int32_t>(mtz.data[row + 1]);
        r.l = static_cast<int32_t>(mtz.data[row + 2]);
        r.I = f * f;
        r.sigma = NAN;
        r.d = 0.0f;

        result.emplace_back(r);
    }

    return result;
}