r.is_not_null.html)
      * [ polars.Expr.is_null ](../../expressions/api/polars.Expr.is_null.html)
      * [ polars.Expr.is_unique ](../../expressions/api/polars.Expr.is_unique.html)
      * [ polars.Expr.not_ ](../../expressions/api/polars.Expr.not_.html)
    * [ Categories ](../../expressions/categories.html) __
      * [ polars.Expr.cat.get_categories ](../../expressions/api/polars.Expr.cat.get_categories.html)
      * [ polars.Expr.cat.set_ordering ](../../expressions/api/polars.Expr.cat.set_ordering.html)
    * [ Columns / names ](../../expressions/columns.html) __
      * [ polars.Expr.alias ](../../expressions/api/polars.Expr.alias.html)
      * [ polars.Expr.exclude ](../../expressions/api/polars.Expr.exclude.html)
      * [ polars.Expr.keep_name ](../../expressions/api/polars.Expr.keep_name.html)
      * [ polars.Expr.map_alias ](../../expressions/api/polars.Expr.map_alias.html)
      * [ polars.Expr.prefix ](../../expressions/api/polars.Expr.prefix.html)
      * [ polars.Expr.suffix ](../../expressions/api/polars.Expr.suffix.html)
      * [ polars.col ](../../expressions/col.html)
    * [ Computation ](../../expressions/computation.html) __
      * [ polars.Expr.abs ](../../expressions/api/polars.Expr.abs.html)
      * [ polars.Expr.approx_n_unique ](../../expressions/api/polars.Expr.approx_n_unique.html)
      * [ polars.Expr.arccos ](../../expressions/api/polars.Expr.arccos.html)
      * [ polars.Expr.arccosh ](../../expressions/api/polars.Expr.arccosh.html)
      * [ polars.Expr.arcsin ](../../expressions/api/polars.Expr.arcsin.html)
      * [ polars.Expr.arcsinh ](../../expressions/api/polars.Expr.arcsinh.html)
      * [ polars.Expr.arctan ](../../expressions/api/polars.Expr.arctan.html)
      * [ polars.Expr.arctanh ](../../expressions/api/polars.Expr.arctanh.html)
      * [ polars.Expr.arg_unique ](../../expressions/api/polars.Expr.arg_unique.html)
      * [ polars.Expr.cbrt ](../../expressions/api/polars.Expr.cbrt.html)
      * [ polars.Expr.cos ](../../expressions/api/polars.Expr.cos.html)
      * [ polars.Expr.cosh ](../../expressions/api/polars.Expr.cosh.html)
      * [ polars.Expr.cot ](../../expressions/api/polars.Expr.cot.html)
      * [ polars.Expr.cum_count ](../../expressions/api/polars.Expr.cum_count.html)
      * [ polars.Expr.cum_max ](../../expressions/api/polars.Expr.cum_max.html)
      * [ polars.Expr.cum_min ](../../expressions/api/polars.Expr.cum_min.html)
      * [ polars.Expr.cum_prod ](../../expressions/api/polars.Expr.cum_prod.html)
      * [ polars.Expr.cum_sum ](../../expressions/api/polars.Expr.cum_sum.html)
      * [ polars.Expr.cumcount ](../../expressions/api/polars.Expr.cumcount.html)
      * [ polars.Expr.cummax ](../../expressions/api/polars.Expr.cummax.html)
      * [ polars.Expr.cummin ](../../expressions/api/polars.Expr.cummin.html)
      * [ polars.Expr.cumprod ](../../expressions/api/polars.Expr.cumprod.html)
      * [ polars.Expr.cumsum ](../../expressions/api/polars.Expr.cumsum.html)
      * [ polars.Expr.cumulative_eval ](../../expressions/api/polars.Expr.cumulative_eval.html)
      * [ polars.Expr.degrees ](../../expressions/api/polars.Expr.degrees.html)
      * [ polars.Expr.diff ](../../expressions/api/polars.Expr.diff.html)
      * [ polars.Expr.dot ](../../expressions/api/polars.Expr.dot.html)
      * [ polars.Expr.entropy ](../../expressions/api/polars.Expr.entropy.html)
      * [ polars.Expr.ewm_mean ](../../expressions/api/polars.Expr.ewm_mean.html)
      * [ polars.Expr.ewm_mean_by ](../../expressions/api/polars.Expr.ewm_mean_by.html)
      * [ polars.Expr.ewm_std ](../../expressions/api/polars.Expr.ewm_std.html)
      * [ polars.Expr.ewm_var ](../../expressions/api/polars.Expr.ewm_var.html)
      * [ polars.Expr.exp ](../../expressions/api/polars.Expr.exp.html)
      * [ polars.Expr.hash ](../../expressions/api/polars.Expr.hash.html)
      * [ polars.Expr.hist ](../../expressions/api/polars.Expr.hist.html)
      * [ polars.Expr.kurtosis ](../../expressions/api/p