diff --git a/src/scgenerator/math.py b/src/scgenerator/math.py
index 6e1b0c5..61c1150 100644
--- a/src/scgenerator/math.py
+++ b/src/scgenerator/math.py
@@ -3,6 +3,7 @@ from typing import Union
 import numpy as np
 from scipy.interpolate import griddata, interp1d
 from scipy.special import jn_zeros
+from .utils.cache import np_cache
 
 
 def span(*vec):
@@ -89,6 +90,85 @@ def u_nm(n, m):
     return jn_zeros(n - 1, m)[-1]
 
 
+@np_cache
+def nfft_matrix(t: np.ndarray, f: np.ndarray) -> np.ndarray:
+    """creates the nfft matrix
+
+    Parameters
+    ----------
+    t : np.ndarray, shape = (n,)
+        time array
+    f : np.ndarray, shape = (m,)
+        frequency array
+
+    Returns
+    -------
+    np.ndarray, shape = (m, n)
+        multiply x(t) by this matrix to get ~X(f)
+    """
+    P, F = np.meshgrid(t, f)
+    return np.exp(-2j * np.pi * P * F)
+
+
+@np_cache
+def infft_matrix(t: np.ndarray, f: np.ndarray) -> np.ndarray:
+    """creates the nfft matrix
+
+    Parameters
+    ----------
+    t : np.ndarray, shape = (n,)
+        time array
+    f : np.ndarray, shape = (m,)
+        frequency array
+
+    Returns
+    -------
+    np.ndarray, shape = (m, n)
+        multiply ~X(f) by this matrix to get x(t)
+    """
+    return np.linalg.pinv(nfft_matrix(t, f))
+
+
+def nfft(t: np.ndarray, s: np.ndarray, f: np.ndarray) -> np.ndarray:
+    """computes the Fourier transform of an uneven signal
+
+    Parameters
+    ----------
+    t : np.ndarray, shape = (n,)
+        time array
+    s : np.ndarray, shape = (n, )
+        amplitute at each point of t
+    f : np.ndarray, shape = (m, )
+        desired frequencies
+
+    Returns
+    -------
+    np.ndarray, shape = (m, )
+        amplitude at each frequency
+    """
+    return nfft_matrix(t, f) @ s
+
+
+def infft(f: np.ndarray, a: np.ndarray, t: np.ndarray) -> np.ndarray:
+    """computes the inverse Fourier transform of an uneven spectrum
+
+    Parameters
+    ----------
+    f : np.ndarray, shape = (n,)
+        frequency array
+    a : np.ndarray, shape = (n, )
+        amplitude at each point of f
+    t : np.ndarray, shape = (m, )
+        time array
+
+    Returns
+    -------
+    np.ndarray, shape = (m, )
+        amplitude at each point of t
+    """
+    return infft_matrix(t, f) @ a
+
+
 def make_uniform_2D(values, x_axis, y_axis, n=1024, method="linear"):
     """Interpolates a 2D array with the help of griddata
     Parameters
diff --git a/src/scgenerator/physics/fiber.py b/src/scgenerator/physics/fiber.py
index edb218f..d08e529 100644
--- a/src/scgenerator/physics/fiber.py
+++ b/src/scgenerator/physics/fiber.py
@@ -9,7 +9,7 @@ from scipy.interpolate import interp1d
 from .. import io
 from ..math import abs2, argclosest, power_fact, u_nm
 from ..utils.parameter import BareParams, hc_model_specific_parameters
-from ..utils import np_cache
+from ..utils.cache import np_cache
 from . import materials as mat
 from . import units
 from .units import c, pi
diff --git a/src/scgenerator/physics/units.py b/src/scgenerator/physics/units.py
index a9cb97b..f832c15 100644
--- a/src/scgenerator/physics/units.py
+++ b/src/scgenerator/physics/units.py
@@ -3,7 +3,8 @@
 # to be used especially when giving plotting ranges : (400, 1400, nm), (-4, 8, ps), ...
 
 from typing import Callable, Union
-
+from dataclasses import dataclass
+from ..utils.parameter import Parameter, type_checker
 import numpy as np
 from numpy import pi
 
@@ -224,6 +225,18 @@ def get_unit(unit: Union[str, Callable]) -> Callable[[float], float]:
     return unit
 
 
+def is_unit(name, value):
+    if not hasattr(get_unit(value), "inv"):
+        raise TypeError("invalid unit specified")
+
+
+@dataclass
+class PlotRange:
+    left: float = Parameter(type_checker(int, float))
+    right: float = Parameter(type_checker(int, float))
+    unit: Callable[[float], float] = Parameter(is_unit, converter=get_unit)
+
+
 def beta2_coef(beta):
     fac = 1e27
     out = np.zeros_like(beta)
@@ -263,45 +276,49 @@ def standardize_dictionary(dico):
     return dico
 
 
-def sort_axis(axis, plt_range):
+def sort_axis(axis, plt_range: PlotRange):
     """
     given an axis, returns this axis cropped according to the given range, converted and sorted
+
     Parameters
     ----------
-        axis : 1D array containing the original axis (usual the w or t array)
-        plt_range : tupple (min, max, conversion_function) used to crop the axis
+    axis : 1D array containing the original axis (usual the w or t array)
+    plt_range : tupple (min, max, conversion_function) used to crop the axis
+
     Returns
-    ----------
-        cropped : the axis cropped, converted and sorted
-        indices : indices to use to slice and sort other array in the same fashion
-        extent : tupple with min and max of cropped
+    -------
+    cropped : the axis cropped, converted and sorted
+    indices : indices to use to slice and sort other array in the same fashion
+    extent : tupple with min and max of cropped
+
     Example
-    ----------
-        w = np.append(np.linspace(0, -10, 20), np.linspace(0, 10, 20))
-        t = np.linspace(-10, 10, 400)
-        W, T = np.meshgrid(w, t)
-        y = np.exp(-W**2 - T**2)
+    -------
+    w = np.append(np.linspace(0, -10, 20), np.linspace(0, 10, 20))
+    t = np.linspace(-10, 10, 400)
+    W, T = np.meshgrid(w, t)
+    y = np.exp(-W**2 - T**2)
 
-        # Define ranges
-        rw = (-4, 4, s)
-        rt = (-2, 6, s)
+    # Define ranges
+    rw = (-4, 4, s)
+    rt = (-2, 6, s)
 
-        w, cw = sort_axis(w, rw)
-        t, ct = sort_axis(t, rt)
+    w, cw = sort_axis(w, rw)
+    t, ct = sort_axis(t, rt)
 
-        # slice y according to the given ranges
-        y = y[ct][:, cw]
+    # slice y according to the given ranges
+    y = y[ct][:, cw]
     """
 
-    r = np.array(plt_range[:2], dtype="float")
-    func = get_unit(plt_range[2])
+    r = np.array((plt_range.left, plt_range.right), dtype="float")
 
-    indices = np.arange(len(axis))[(axis <= np.max(func(r))) & (axis >= np.min(func(r)))]
+    indices = np.arange(len(axis))[
+        (axis <= np.max(plt_range.unit(r))) & (axis >= np.min(plt_range.unit(r)))
+    ]
     cropped = axis[indices]
-    order = np.argsort(func.inv(cropped))
+    order = np.argsort(plt_range.unit.inv(cropped))
     indices = indices[order]
     cropped = cropped[order]
-    out_ax = func.inv(cropped)
+    out_ax = plt_range.unit.inv(cropped)
 
     return out_ax, indices, (out_ax[0], out_ax[-1])
 
diff --git a/src/scgenerator/plotting.py b/src/scgenerator/plotting.py
index 864489c..3de9cba 100644
--- a/src/scgenerator/plotting.py
+++ b/src/scgenerator/plotting.py
@@ -248,14 +248,13 @@ def _finish_plot_2D(
     ax,
     file_name,
     file_type,
-    params,
 ):
 
     # apply log transform if required
-    if log != False:
+    if log is not False:
         vmax = defaults["vmax"] if vmax is None else vmax
         vmin = defaults["vmin"] if vmin is None else vmin
-        if isinstance(log, (float, int)) and log != True:
+        if isinstance(log, (float, int)) and log is not True:
             values = units.to_log(values, ref=log)
 
         elif log == "2D":
@@ -338,7 +337,7 @@ def _finish_plot_2D(
         fig.savefig(out_path, bbox_inches="tight", dpi=200)
         print(f"plot saved in {out_path}")
     if cbar_label is not None:
-        return fig, ax, cbar.ax
+        return fig, (ax, cbar.ax)
     else:
         return fig, ax
 
@@ -355,7 +354,7 @@ def plot_spectrogram(
     vmax: float = None,
     cbar_label: str = "normalized intensity (dB)",
     file_type: str = "png",
-    file_name: str = None,
+    file_name: str = "plot",
     cmap: str = None,
     ax: plt.Axes = None,
 ):
@@ -448,13 +447,12 @@ def plot_spectrogram(
         ax,
         file_name,
         file_type,
-        params,
     )
 
 
 def plot_results_2D(
     values: np.ndarray,
-    plt_range: RangeType,
+    plt_range: Union[units.PlotRange, tuple],
     params: BareParams,
     log: Union[int, float, bool, str] = "1D",
     skip: int = 16,
@@ -463,7 +461,7 @@ def plot_results_2D(
     transpose: bool = False,
     cbar_label: Optional[str] = "normalized intensity (dB)",
     file_type: str = "png",
-    file_name: str = None,
+    file_name: str = "plot",
     cmap: str = None,
     ax: plt.Axes = None,
 ):
@@ -528,7 +526,7 @@ def plot_results_2D(
         values = abs2(values)
 
     # make uniform if converting to wavelength
-    if plt_range[2].type == "WL":
+    if plt_range.unit.type == "WL":
         if is_spectrum:
             values = np.apply_along_axis(units.to_WL, 1, values, params.frep, x_axis)
         values = np.array(
@@ -554,7 +552,7 @@ def plot_results_2D(
     return _finish_plot_2D(
         values,
         x_axis,
-        plt_range[2].label,
+        plt_range.unit.label,
         params.z_targets,
         "propagation distance (m)",
         log,
@@ -566,13 +564,12 @@ def plot_results_2D(
         ax,
         file_name,
         file_type,
-        params,
     )
 
 
 def plot_results_1D(
     values: np.ndarray,
-    plt_range: RangeType,
+    plt_range: Union[units.PlotRange, tuple],
     params: BareParams,
     log: Union[str, int, float, bool] = False,
     spacing: Union[int, float] = 1,
@@ -586,7 +583,7 @@ def plot_results_1D(
     line_label: str = None,
     transpose: bool = False,
     **line_kwargs,
-):
+) -> tuple[plt.Figure, plt.Axes, np.ndarray, np.ndarray]:
     """
 
     Parameters
@@ -649,7 +646,7 @@ def plot_results_1D(
     values *= yscaling
 
     # make uniform if converting to wavelength
-    if plt_range[2].type == "WL":
+    if plt_range.unit.type == "WL":
         if is_spectrum:
             values = units.to_WL(values, params.frep, units.m.inv(params.w[ind]))
 
@@ -687,12 +684,12 @@ def plot_results_1D(
         ax.yaxis.set_label_position("right")
         ax.set_xlim(vmax, vmin)
         ax.set_xlabel(ylabel)
-        ax.set_ylabel(plt_range[2].label)
+        ax.set_ylabel(plt_range.unit.label)
     else:
         ax.plot(x_axis, values, label=line_label, **line_kwargs)
         ax.set_ylim(vmin, vmax)
         ax.set_ylabel(ylabel)
-        ax.set_xlabel(plt_range[2].label)
+        ax.set_xlabel(plt_range.unit.label)
 
     if is_new_plot:
         fig.savefig(out_path, bbox_inches="tight", dpi=200)
@@ -700,10 +697,13 @@ def plot_results_1D(
     return fig, ax, x_axis, values
 
 
-def _prep_plot(values: np.ndarray, plt_range: RangeType, params: BareParams):
+def _prep_plot(
+    values: np.ndarray, plt_range: Union[units.PlotRange, tuple], params: BareParams
+) -> tuple[bool, np.ndarray, units.PlotRange]:
     is_spectrum = values.dtype == "complex"
-    plt_range = (*plt_range[:2], units.get_unit(plt_range[2]))
-    if plt_range[2].type in ["WL", "FREQ", "AFREQ"]:
+    if not isinstance(plt_range, units.PlotRange):
+        plt_range = units.PlotRange(*plt_range)
+    if plt_range.unit.type in ["WL", "FREQ", "AFREQ"]:
         x_axis = params.w.copy()
     else:
         x_axis = params.t.copy()
@@ -712,7 +712,7 @@ def _prep_plot(values: np.ndarray, plt_range: RangeType, params: BareParams):
 
 def plot_avg(
     values: np.ndarray,
-    plt_range: RangeType,
+    plt_range: Union[units.PlotRange, tuple],
     params: BareParams,
     log: Union[float, int, str, bool] = False,
     spacing: Union[float, int] = 1,
@@ -809,7 +809,7 @@ def plot_avg(
         values = abs2(values)
     values *= yscaling
     mean_values = np.mean(values, axis=0)
-    if plt_range[2].type == "WL" and renormalize:
+    if plt_range.unit.type == "WL" and renormalize:
         values = np.apply_along_axis(units.to_WL, 1, values, params.frep, x_axis)
         mean_values = units.to_WL(mean_values, params.frep, x_axis)
 
@@ -886,7 +886,7 @@ def plot_avg(
         top.set_ylim(*ext)
         bot.yaxis.tick_right()
         bot.yaxis.set_label_position("right")
-        bot.set_ylabel(plt_range[2].label)
+        bot.set_ylabel(plt_range.unit.label)
         bot.set_ylim(*ext)
     else:
         for value in values:
@@ -898,7 +898,7 @@ def plot_avg(
         top.set_ylim(bottom=vmin, top=vmax)
         top.set_ylabel(ylabel)
         top.set_xlim(*ext)
-        bot.set_xlabel(plt_range[2].label)
+        bot.set_xlabel(plt_range.unit.label)
         bot.set_xlim(*ext)
 
     custom_lines = [
@@ -961,7 +961,7 @@ def prepare_plot_1D(values, plt_range, x_axis, yscaling=1, spacing=1, frep=80e6)
 
     values = values[:, ind]
 
-    if plt_range[2].type == "WL":
+    if plt_range.unit.type == "WL":
         values = np.apply_along_axis(units.to_WL, -1, values, frep, x_axis)
 
     if isinstance(spacing, float):
diff --git a/src/scgenerator/spectra.py b/src/scgenerator/spectra.py
index 159c590..6329256 100644
--- a/src/scgenerator/spectra.py
+++ b/src/scgenerator/spectra.py
@@ -1,14 +1,16 @@
 import os
 from collections.abc import Sequence
 from pathlib import Path
-from typing import Dict
+from re import UNICODE
+from typing import Callable, Dict, Iterable, Optional, Union
 
 import numpy as np
 
 from . import initialize, io, math
+from .physics import units
 from .const import SPECN_FN
 from .logger import get_logger
-from .plotting import units
+from .plotting import plot_avg, plot_results_1D, plot_results_2D
 
 
 class Spectrum(np.ndarray):
@@ -158,13 +160,12 @@ class Pulse(Sequence):
         Parameters
         ----------
         ind : int or list of int
-        if only certain spectra are desired.
-                - If left to None, returns every spectrum
-                - If only 1 int, will cast the (1, n, nt) array into a (n, nt) array
+            if only certain spectra are desired
         Returns
         ----------
-        spectra : array
-            squeezed array of complex spectra (n simulation on a nt size grid at each ind)
+        spectra : array of shape (nz, m, nt)
+            array of complex spectra (pulse at nz positions consisting
+            of nm simulation on a nt size grid)
         """
 
         self.logger.debug(f"opening {self.path}")
@@ -200,3 +201,46 @@ class Pulse(Sequence):
         spec = Spectrum(spec, self.wl, self.params.frep)
         self.cache[i] = spec
         return spec
+
+    def plot_2D(
+        self,
+        left: float,
+        right: float,
+        unit: Union[Callable[[float], float], str],
+        z_ind: Union[int, Iterable[int]] = None,
+        sim_ind: int = 0,
+        **kwargs,
+    ):
+        plt_range, vals = self.retrieve_plot_values(left, right, unit, z_ind, sim_ind)
+        return plot_results_2D(vals, plt_range, self.params, **kwargs)
+
+    def plot_1D(
+        self,
+        left: float,
+        right: float,
+        unit: Union[Callable[[float], float], str],
+        z_ind: int,
+        sim_ind: int = 0,
+        **kwargs,
+    ):
+        plt_range, vals = self.retrieve_plot_values(left, right, unit, z_ind, sim_ind)
+        return plot_results_1D(vals[0], plt_range, self.params, **kwargs)
+
+    def plot_avg(
+        self,
+        left: float,
+        right: float,
+        unit: Union[Callable[[float], float], str],
+        z_ind: int,
+        **kwargs,
+    ):
+        plt_range, vals = self.retrieve_plot_values(left, right, unit, z_ind, slice(None))
+        return plot_avg(vals, plt_range, self.params, **kwargs)
+
+    def retrieve_plot_values(self, left, right, unit, z_ind, sim_ind):
+        plt_range = units.PlotRange(left, right, unit)
+        if plt_range.unit.type == "TIME":
+            vals = self.all_fields(ind=z_ind)[:, sim_ind]
+        else:
+            vals = self.all_spectra(ind=z_ind)[:, sim_ind]
+        return plt_range, vals
diff --git a/src/scgenerator/utils/__init__.py b/src/scgenerator/utils/__init__.py
index 00750f4..7c81e99 100644
--- a/src/scgenerator/utils/__init__.py
+++ b/src/scgenerator/utils/__init__.py
@@ -283,61 +283,3 @@ def override_config(new: Dict[str, Any], old: BareConfig = None) -> BareConfig:
     for k in new:
         variable.pop(k, None)  # remove old ones
     return replace(old, variable=variable, **{k: None for k in variable}, **new)
-
-
-# def np_cache(function):
-#     """applies functools.cache to function that take numpy arrays as input"""
-
-#     @cache
-#     def cached_wrapper(*hashable_args, **hashable_kwargs):
-#         args = tuple(np.array(arg) if isinstance(arg, tuple) else arg for arg in hashable_args)
-#         kwargs = {
-#             k: np.array(kwarg) if isinstance(kwarg, tuple) else kwarg
-#             for k, kwarg in hashable_kwargs.items()
-#         }
-#         return function(*args, **kwargs)
-
-#     @wraps(function)
-#     def wrapper(*args, **kwargs):
-#         hashable_args = tuple(tuple(arg) if isinstance(arg, np.ndarray) else arg for arg in args)
-#         hashable_kwargs = {
-#             k: tuple(kwarg) if isinstance(kwarg, np.ndarray) else kwarg
-#             for k, kwarg in kwargs.items()
-#         }
-#         return cached_wrapper(*hashable_args, **hashable_kwargs)
-
-#     # copy lru_cache attributes over too
-#     wrapper.cache_info = cached_wrapper.cache_info
-#     wrapper.cache_clear = cached_wrapper.cache_clear
-
-#     return wrapper
-
-
-class np_cache:
-    def __init__(self, function):
-        self.logger = get_logger(__name__)
-        self.func = function
-        self.cache = {}
-        self.hits = 0
-        self.misses = 0
-        update_wrapper(self, function)
-
-    def __call__(self, *args, **kwargs):
-        hashable_args = tuple(
-            tuple(arg) if isinstance(arg, (np.ndarray, list)) else arg for arg in args
-        )
-        hashable_kwargs = tuple(
-            {
-                k: tuple(kwarg) if isinstance(kwarg, (np.ndarray, list)) else kwarg
-                for k, kwarg in kwargs.items()
-            }.items()
-        )
-        key = hash((hashable_args, hashable_kwargs))
-        if key not in self.cache:
-            self.logger.debug("cache miss")
-            self.misses += 1
-            self.cache[key] = self.func(*args, **kwargs)
-        else:
-            self.hits += 1
-            self.logger.debug("cache hit")
-        return copy(self.cache[key])
diff --git a/src/scgenerator/utils/cache.py b/src/scgenerator/utils/cache.py
new file mode 100644
index 0000000..fbc4ee7
--- /dev/null
+++ b/src/scgenerator/utils/cache.py
@@ -0,0 +1,75 @@
+from collections import namedtuple
+from copy import copy
+from functools import wraps
+import numpy as np
+
+CacheInfo = namedtuple("CacheInfo", "hits misses size")
+
+
+def np_cache(func):
+    def new_cached_func():
+        cache = {}
+        hits = misses = 0
+
+        @wraps(func)
+        def wrapped(*args, **kwargs):
+            nonlocal cache, hits, misses
+            hashable_args = tuple(
+                tuple(arg) if isinstance(arg, (np.ndarray, list)) else arg for arg in args
+            )
+            hashable_kwargs = tuple(
+                {
+                    k: tuple(kwarg) if isinstance(kwarg, (np.ndarray, list)) else kwarg
+                    for k, kwarg in kwargs.items()
+                }.items()
+            )
+            key = hash((hashable_args, hashable_kwargs))
+            if key not in cache:
+                misses += 1
+                cache[key] = func(*args, **kwargs)
+            else:
+                hits += 1
+            return copy(cache[key])
+
+        def reset():
+            nonlocal cache, hits, misses
+            cache = {}
+            hits = misses = 0
+
+        wrapped.cache_info = lambda: CacheInfo(hits, misses, len(cache))
+        wrapped.reset = reset
+
+        return wrapped
+
+    return new_cached_func()
+
+
+if __name__ == "__main__":
+    import random
+    import time
+
+    @np_cache
+    def lol(a):
+        time.sleep(random.random() * 4)
+        return a / 2
+
+    @np_cache
+    def ggg(b):
+        time.sleep(random.random() * 4)
+        return b * 2
+
+    x = np.arange(6)
+    for i in range(5):
+        print(lol.cache_info())
+        print(lol(x))
+
+    print(f"{ggg.cache_info()=}")
+    print(f"{lol.cache_info()=}")
+    lol.reset()
+
+    print(ggg(np.arange(3)))
+    print(ggg(np.arange(8)))
+    print(ggg(np.arange(3)))
+
+    print(f"{ggg.cache_info()=}")
+    print(f"{lol.cache_info()=}")