Syntax error in plt.gcf(). Used on geographical climate dataset - matplotlib

Question

I am attempting to plot a downloaded .nc file containing geographical climate data.
In the last step, I get a syntax error for the following line: plt.gcf().set_size_inches(20,10). I cannot seem to locate the error.
After successfully downloading the file, this is the code I used to plot the data:
import numpy as np
import xarray # used for reading the data.
import matplotlib.pyplot as plt # used to plot the data.
import ipywidgets as widgets # For ease in selecting variables.
import cartopy.crs as ccrs # Used to georeference data.
filelist_arr = [save_dir + os.path.basename(file) for file in filelist]
selected_file = widgets.Dropdown(options=filelist_arr, description='data file')
display(selected_file)
# Now to load in the data to xarray
ds = xarray.open_dataset(selected_file.value)
# Helper methods# Define function to get standard dimensions
def get_time(dataset):
for _,cur_coord in dataset.coords.items:
if cur_coord.attrs['standard_name'] == 'time':
return cur_coord
def get_lat(dataset):
for _,cur_coord in dataset.coords.items:
if cur_coord.attrs['standard_name'] == 'longitude':
return cur_coord
def get_lon(dataset):
for _,cur_coord in dataset.coords.items:
if cur_coord.attrs['standard_name'] == 'latitude':
return cur_coord
def get_primary(dataset):
primary_variables = {}
coords = dataset.coords.keys()
highest_dims = 0
for cur_key,cur_var in dataset.variables.items():
if cur_key not in coords:
primary_variables[cur_key] = cur_var
return primary_variables
var = widgets.Dropdown(
options=get_primary(ds).keys(),
description='Variable')
display(var)
So far so good. Now, in the final block, I get a syntax error in line 3.
var = widgets.Dropdown(
proj = ccrs.Mercator()
plt.gcf().set_size_inches(20,10)
ax = plt.axes(projection=proj)
data_slice = ds[var.value].isel(time=10)
data_slice.plot.contourf(ax=ax, transform=ccrs.PlateCarree())
ax.set_global()
ax.coastlines()
This is the error:
File "<ipython-input-80-8848cc5cc689>", line 3
plt.gcf().set_size_inches(20,10)
^
SyntaxError: invalid syntax
Can anybody explain what I am doing wrong?

Answer 1

I think you got a little bit confused by trying to wrap the code inside the widgets.Dropdown() code.
Perhaps it's a good idea to write the code without widgets first, and then add them later if your code works. Can you try the following code, and see which errors appears then:
import numpy as np
import xarray
import matplotlib.pyplot as plt
import ipywidgets as widgets
import cartopy.crs as ccrs
# Load data into memory
filelist_arr = [save_dir + os.path.basename(file) for file in filelist]
selected_file = widgets.Dropdown(options=filelist_arr, description='data file')
# Create xarray
ds = xarray.open_dataset(selected_file.value)
# Helper methods
def get_time(dataset):
for _,cur_coord in dataset.coords.items:
if cur_coord.attrs['standard_name'] == 'time':
return cur_coord
def get_lat(dataset):
for _,cur_coord in dataset.coords.items:
if cur_coord.attrs['standard_name'] == 'longitude':
return cur_coord
def get_lon(dataset):
for _,cur_coord in dataset.coords.items:
if cur_coord.attrs['standard_name'] == 'latitude':
return cur_coord
def get_primary(dataset):
primary_variables = {}
coords = dataset.coords.keys()
highest_dims = 0
for cur_key,cur_var in dataset.variables.items():
if cur_key not in coords:
primary_variables[cur_key] = cur_var
return primary_variables
# Ask user to select dataset
var = widgets.Dropdown(
options=get_primary(ds).keys(),
description='Variable')
display(var)
# Initialize new figure and specify figure size
plt.figure(num=None, figsize=(20, 10))
# Create Mercator projection with dateline in the middle
ax = plt.axes(projection=ccrs.Mercator(central_longitude=180))
# Draw coastlines
ax.coastlines()
# Select the appropriate data and plot to the axes
data_slice = ds[var.value].isel(time=10)
data_slice.plot.contourf(ax=ax, transform=ccrs.PlateCarree())
# Optional: set the map extent, for geographical coordinates
# ax.set_extent([90, 270, -40, 40], crs=ccrs.PlateCarree())
# Optional: add title
# plt.title('Geographical climate data at time = 10')
# Show the plot
plt.show()
If this still gives an error, please let me know in the comments below.