# How to use NumPy slices in 2d for PyPlot's GridSpec
**URL:** https://discourse.julialang.org/t/how-to-use-numpy-slices-in-2d-for-pyplots-gridspec/40023
**Category:** General Usage
**Tags:** question, pyplot
**Created:** [May 23, 2020, 2:24pm UTC](https://discourse.julialang.org/t/how-to-use-numpy-slices-in-2d-for-pyplots-gridspec/40023 "2020-05-23T14:24:45Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@roi.holtzman](https://discourse.julialang.org/u/roi.holtzman)
#### Post date: [May 23, 2020, 2:24pm UTC](https://discourse.julialang.org/t/how-to-use-numpy-slices-in-2d-for-pyplots-gridspec/40023/1 "2020-05-23T14:24:45Z")
I am trying to create a plot with multiple subplots in `PyPlot`. For that I am using `matplotlib`’s [`GridSpec`](https://matplotlib.org/3.2.1/tutorials/intermediate/gridspec.html).
Some of the usage is given by `NumPy` slices as seen in their example from the [docs](https://matplotlib.org/3.2.1/tutorials/intermediate/gridspec.html):
```julia
fig8 = plt.figure(constrained_layout=False)
gs1 = fig8.add_gridspec(nrows=3, ncols=3, left=0.05, right=0.48, wspace=0.05)
f8_ax1 = fig8.add_subplot(gs1[:-1, :])
f8_ax2 = fig8.add_subplot(gs1[-1, :-1])
f8_ax3 = fig8.add_subplot(gs1[-1, -1])
```
It was shown [here](https://github.com/JuliaPy/PyPlot.jl/issues/149) that slicing can be done by
```julia
f8_ax1 = fig8.add_subplot(get(gs1, pycall(pybuiltin("slice"), PyObject, 0,3)))
```
The above line is equivalent to `gs1[0, 0:3]`.
But my question is, how can I do it in 2d? I mean how can I slice for example `gs1[0:2, 0:3]`?
---
### Author:  [@hcarlsso](https://discourse.julialang.org/u/hcarlsso)
#### Post date: [September 30, 2020, 1:38pm UTC](https://discourse.julialang.org/t/how-to-use-numpy-slices-in-2d-for-pyplots-gridspec/40023/2 "2020-09-30T13:38:51Z")
Use a combination of `get` and `pybuiltin("slice")`
```julia
using PyPlot
using PyCall
fig = figure()
gs = fig.add_gridspec(2,2)
element(i,j) = get(gs, (i,j))
slice(i,j) = pycall(pybuiltin("slice"), PyObject, i,j)
ax = fig.add_subplot(element(0,0))
ax.plot(sin.(-pi:0.1:pi))
ax = fig.add_subplot(element(0,1))
ax.plot(cos.(-pi:0.1:pi))
ax = fig.add_subplot(element(1,slice(0,2)))
ax.plot(-pi:0.1:pi |> collect)
```
---
### Author:  [@junix](https://discourse.julialang.org/u/junix)
#### Post date: [June 15, 2025, 12:42pm UTC](https://discourse.julialang.org/t/how-to-use-numpy-slices-in-2d-for-pyplots-gridspec/40023/3 "2025-06-15T12:42:00Z")
A convenient wrapper:
```julia
import PyPlot as plt; using PyPlot: @L_str, @py_str, @pyinclude, pyimport, pycall, PyDict, pybuiltin, PyObject
gridspec = pyimport("matplotlib.gridspec")
slice(args...) = pycall(pybuiltin("slice"), PyObject, args...)
# Wrapper struct for matplotlib GridSpec with Julia-style indexing
struct JulianGridSpec
gs::PyObject # Python GridSpec object
end
# Enable Julia-style indexing (1-based) on GridSpec objects
function Base.getindex(jgs::JulianGridSpec, i::Union{Int, UnitRange, Colon}, j::Union{Int, UnitRange, Colon})
# Convert Julia indices to Python 0-based indices
py_i = to_python_index(i)
py_j = to_python_index(j)
return get(jgs.gs, (py_i, py_j))
end
# Convert Julia integer to Python 0-based index
function to_python_index(idx::Int)
return idx - 1
end
# Convert Julia range to Python slice
function to_python_index(idx::UnitRange)
return slice(idx.start - 1, idx.stop)
end
# Convert Julia colon to Python slice(None)
function to_python_index(::Colon)
return slice(nothing)
end
# Create figure and GridSpec layout
fig = plt.figure(figsize=(12, 10))
gs = gridspec.GridSpec(4, 2, figure=fig)
# Use Julia-style indexing with the wrapper
jgs = JulianGridSpec(gs)
ax1 = fig.add_subplot(jgs[1, 1:2]) # Row 1, columns 1-2
ax2 = fig.add_subplot(jgs[2:4, 1]) # Rows 2-4, column 1
```
---
### Author:  [@junix](https://discourse.julialang.org/u/junix)
#### Post date: [June 15, 2025, 1:06pm UTC](https://discourse.julialang.org/t/how-to-use-numpy-slices-in-2d-for-pyplots-gridspec/40023/4 "2025-06-15T13:06:52Z")
```julia
module GridSpec
# Export the main struct and functions that users need
export JulianGridSpec, gridspec
using PyCall:pyimport, pycall, pybuiltin, PyObject
# Import matplotlib's gridspec module
const gridspec = pyimport("matplotlib.gridspec")
# Julia wrapper for Python's slice function
slice(args...) = pycall(pybuiltin("slice"), PyObject, args...)
# Wrapper struct for matplotlib GridSpec with Julia-style indexing
struct JulianGridSpec
gs::PyObject # Python GridSpec object
end
# Support for `end` keyword - implement lastindex
function Base.lastindex(jgs::JulianGridSpec, dim::Int)
if dim == 1
return jgs.gs.nrows
elseif dim == 2
return jgs.gs.ncols
else
error("GridSpec only has 2 dimensions")
end
end
# Enable Julia-style indexing (1-based) on GridSpec objects
function Base.getindex(jgs::JulianGridSpec, i::Union{Int, UnitRange, Colon}, j::Union{Int, UnitRange, Colon})
# Convert Julia indices to Python 0-based indices
py_i = to_python_index(i)
py_j = to_python_index(j)
return get(jgs.gs, (py_i, py_j))
end
# Convert Julia integer to Python 0-based index
function to_python_index(idx::Int)
return idx - 1
end
# Convert Julia range to Python slice
function to_python_index(idx::UnitRange)
return slice(idx.start - 1, idx.stop)
end
# Convert Julia colon to Python slice(None)
function to_python_index(::Colon)
return slice(nothing)
end
end # module
```