clippy: fix len_zero warnings

src/base/construction.rs

@@ -195,7 +195,7 @@ where
     where
         SB: Storage<N, U1, C>,
     {
-        assert!(rows.len() > 0, "At least one row must be given.");
+        assert!(!rows.is_empty(), "At least one row must be given.");
         let nrows = R::try_to_usize().unwrap_or_else(|| rows.len());
         let ncols = rows[0].len();
         assert!(
@@ -237,7 +237,7 @@ where
     where
         SB: Storage<N, R>,
     {
-        assert!(columns.len() > 0, "At least one column must be given.");
+        assert!(!columns.is_empty(), "At least one column must be given.");
         let ncols = C::try_to_usize().unwrap_or(columns.len());
         let nrows = columns[0].len();
         assert!(

src/base/norm.rs

@@ -524,12 +524,12 @@ where
 
         match D::dim() {
             1 => {
-                if vs.len() == 0 {
+                if vs.is_empty() {
                     let _ = f(&Self::canonical_basis_element(0));
                 }
             }
             2 => {
-                if vs.len() == 0 {
+                if vs.is_empty() {
                     let _ = f(&Self::canonical_basis_element(0))
                         && f(&Self::canonical_basis_element(1));
                 } else if vs.len() == 1 {
@@ -542,7 +542,7 @@ where
                 // Otherwise, nothing.
             }
             3 => {
-                if vs.len() == 0 {
+                if vs.is_empty() {
                     let _ = f(&Self::canonical_basis_element(0))
                         && f(&Self::canonical_basis_element(1))
                         && f(&Self::canonical_basis_element(2));

src/base/statistics.rs

@@ -199,7 +199,7 @@ impl<N: Scalar, R: Dim, C: Dim, S: Storage<N, R, C>> Matrix<N, R, C, S> {
     where
         N: Field + SupersetOf<f64>,
     {
-        if self.len() == 0 {
+        if self.is_empty() {
             N::zero()
         } else {
             let val = self.iter().cloned().fold((N::zero(), N::zero()), |a, b| {
@@ -308,7 +308,7 @@ impl<N: Scalar, R: Dim, C: Dim, S: Storage<N, R, C>> Matrix<N, R, C, S> {
     where
         N: Field + SupersetOf<f64>,
     {
-        if self.len() == 0 {
+        if self.is_empty() {
             N::zero()
         } else {
             self.sum() / crate::convert(self.len() as f64)

src/linalg/svd.rs

@@ -108,7 +108,7 @@ where
         max_niter: usize,
     ) -> Option<Self> {
         assert!(
-            matrix.len() != 0,
+            !matrix.is_empty(),
             "Cannot compute the SVD of an empty matrix."
         );
         let (nrows, ncols) = matrix.data.shape();