fast_aug 0.1.0

Fast data augmentation for text
Documentation 
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/// Parameters for augmentation
#[derive(Clone)]
pub struct TextAugmentParameters {
    /// Probability of augmentation of single element
    /// Not true probability, but expected percent of elements to be augmented
    /// If not set fall back to default value of 0.3
    pub p: f32,
    /// Minimum elements for augmentation
    /// If not set - no limit
    pub min_elements: Option<usize>,
    /// Maximum elements for augmentation
    /// If not set - no limit
    pub max_elements: Option<usize>,
}

impl Default for TextAugmentParameters {
    fn default() -> Self {
        TextAugmentParameters {
            p: 0.3,
            min_elements: None,
            max_elements: None,
        }
    }
}

impl TextAugmentParameters {
    /// Create new AugmentParameters
    /// # Arguments
    /// * `p` - Probability of augmentation of single element (expected percent of elements to be augmented)
    /// * `min_elements` - Minimum elements for augmentation
    /// * `max_elements` - Maximum elements for augmentation
    pub fn new(p: f32, min_elements: Option<usize>, max_elements: Option<usize>) -> Self {
        TextAugmentParameters {
            p,
            min_elements,
            max_elements,
        }
    }

    /// Calculate number of elements to be augmented from input size
    ///
    /// # Arguments
    /// * `input_size` - Size of input in elements (words, chars, etc.)
    ///
    /// # Examples
    /// ```rust
    /// use fast_aug::text::TextAugmentParameters;
    ///
    /// let params = TextAugmentParameters{p: 0.5, min_elements: None, max_elements: None};
    /// // Apply only p
    /// assert_eq!(params.num_elements(10), 5);
    ///
    /// let params = TextAugmentParameters{p: 0.5, min_elements: Some(3), max_elements: Some(7)};
    /// // Apply min_elements
    /// assert_eq!(params.num_elements(4), 3);
    /// // Apply min_elements, but reach input_size, so return input_size
    /// assert_eq!(params.num_elements(1), 1);
    /// // Apply max_elements
    /// assert_eq!(params.num_elements(100), 7);
    /// ```
    pub fn num_elements(&self, input_size: usize) -> usize {
        if input_size == 0 || self.p <= 0.0 {
            return 0;
        }

        let prob_num_elements = f32::ceil(self.p * input_size as f32) as usize;

        if let Some(min_elements) = self.min_elements {
            if prob_num_elements < min_elements {
                if input_size < min_elements {
                    return input_size;
                }
                return min_elements;
            }
        }
        if let Some(max_elements) = self.max_elements {
            if prob_num_elements > max_elements {
                return max_elements;
            }
        }
        prob_num_elements
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use test_case::test_case;

    #[test_case(0.0, 10, 0)]
    #[test_case(0.5, 10, 5)]
    #[test_case(1.0, 10, 10)]
    #[test_case(0.5, 0, 0)]
    #[test_case(0.5, 1, 1)]
    fn test_num_elements_only_p(p: f32, input_size: usize, expected: usize) {
        let params = TextAugmentParameters::new(p, None, None);
        assert_eq!(params.num_elements(input_size), expected);
    }

    #[test]
    fn test_num_elements_defaults() {
        let params = TextAugmentParameters::default();
        assert_eq!(params.num_elements(10), 3);
    }

    #[test_case(0.5, 10, 5, 5)]
    #[test_case(0.5, 10, 7, 7)]
    #[test_case(0.5, 10, 10, 10)]
    #[test_case(0.5, 10, 1, 5)]
    #[test_case(0.5, 10, 0, 5)]
    fn test_num_elements_min_limit(p: f32, input_size: usize, min_elements: usize, expected: usize) {
        let params = TextAugmentParameters::new(p, Some(min_elements), None);
        assert_eq!(params.num_elements(input_size), expected);
    }

    #[test]
    fn test_num_elements_min_limit_more_than_input() {
        let params = TextAugmentParameters::new(0.5, Some(10), None);
        assert_eq!(params.num_elements(5), 5);
    }

    #[test_case(0.5, 10, 5, 5)]
    #[test_case(0.5, 10, 7, 5)]
    #[test_case(0.5, 10, 10, 5)]
    #[test_case(0.5, 10, 1, 1)]
    #[test_case(0.5, 10, 0, 0)]
    fn test_num_elements_max_limit(p: f32, input_size: usize, max_elements: usize, expected: usize) {
        let params = TextAugmentParameters::new(p, None, Some(max_elements));
        assert_eq!(params.num_elements(input_size), expected);
    }

    // TODO: test min > max
    #[test_case(0.5, 10, 5, 5, 5)]
    #[test_case(0.5, 10, 3, 3, 3)]
    #[test_case(0.5, 10, 7, 7, 7)]
    #[test_case(0.5, 10, 3, 7, 5)]
    #[test_case(0.5, 10, 0, 3, 3)]
    #[test_case(0.5, 10, 6, 10, 6)]
    fn test_num_elements_min_max_limit(
        p: f32,
        input_size: usize,
        min_elements: usize,
        max_elements: usize,
        expected: usize,
    ) {
        let params = TextAugmentParameters::new(p, Some(min_elements), Some(max_elements));
        assert_eq!(params.num_elements(input_size), expected);
    }
}