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Map (marvin.utils.plot.map)

Introduction

marvin.utils.plot.map contains utility functions for plotting Marvin maps. The main function in this module is ~marvin.utils.plot.map.plot, which is thinly wrapped by the ~marvin.tools.quantities.Map.plot method in the ~marvin.tools.quantities.Map class for convenience.

Getting Started

~marvin.utils.plot.map.plot makes plotting a publication-quality MaNGA map easy with its carefully chosen default parameters.

from marvin.tools.maps import Maps import marvin.utils.plot.map as mapplot

from marvin.tools.maps import Maps import marvin.utils.plot.map as mapplot maps = Maps(plateifu='8485-1901') ha = maps['emline_gflux_ha_6564'] fig, ax = mapplot.plot(dapmap=ha) # == ha.plot()

However, you may want to do further processing of the map, so you can override the default DAP ~marvin.utils.plot.map.plot.value, ~marvin.utils.plot.map.plot.ivar, and/or ~marvin.utils.plot.map.plot.mask with your own arrays.

fig, ax = mapplot.plot(dapmap=ha, value=ha.value * 10.)

A ~marvin.utils.plot.map.plot.dapmap object is not even necessary for ~marvin.utils.plot.map.plot, though if you do not provide a ~marvin.utils.plot.map.plot.dapmap object, then you will need to set a ~marvin.utils.plot.map.plot.value. You will also need to provide other attributes, such as ~marvin.utils.plot.map.plot.title and ~marvin.utils.plot.map.plot.cblabel, that are by default set from attributes of the ~marvin.utils.plot.map.plot.dapmap object.

import numpy as np
fig, ax = mapplot.plot(value=np.random.random((34, 34)), mask=ha.mask)

This flexibilty is especially useful for passing in a custom mask, such as one created with the ~marvin.tools.maps.Maps.get_bpt method. For more explanation of the mask manipulation in this specific example, see the plotting tutorial <marvin-plotting-map-starforming>.

from marvin.tools.maps import Maps masks, __, __ = maps.get_bpt(show_plot=False)

# Create a bitmask for non-star-forming spaxels by taking the # complement (~) of the BPT global star-forming mask (where True == star-forming) # and mark those spaxels as "DONOTUSE". mask_non_sf = ~masks['sf']['global'] * ha.pixmask.labels_to_value('DONOTUSE')

# Do a bitwise OR between DAP mask and non-star-forming mask. mask = ha.mask | mask_non_sf fig, ax = mapplot.plot(dapmap=ha, mask=mask) # == ha.plot(mask=mask)

~marvin.utils.plot.map.plot lets you build multi-panel plots because it accepts pre-defined matplotlib.figure and matplotlib.axes objects.

import matplotlib.pyplot as plt plt.style.use('seaborn-darkgrid') # set matplotlib style sheet

plateifus = ['8485-1901', '7443-12701'] mapnames = ['stellar_vel', 'stellar_sigma']

rows = len(plateifus) cols = len(mapnames) fig, axes = plt.subplots(rows, cols, figsize=(8, 8)) for row, plateifu in zip(axes, plateifus): maps = Maps(plateifu=plateifu) for ax, mapname in zip(row, mapnames): mapplot.plot(dapmap=maps[mapname], fig=fig, ax=ax, title=' '.join((plateifu, mapname)))

fig.tight_layout()

Using ~marvin.utils.plot.map

For more in-depth discussion of using ~marvin.utils.plot.map, please see the following sections:

Plotting Tutorial

  • marvin-plotting-tutorial
    • marvin-plotting-quick-map
    • marvin-plotting-multipanel-single
    • marvin-plotting-multipanel-multiple
    • marvin-plotting-custom-map-cbrange
    • marvin-plotting-custom-map-snr-min
    • marvin-plotting-custom-map-axes
    • Plot Halpha Map of Star-forming Spaxels <marvin-plotting-map-starforming>
    • Plot [NII]/Halpha Flux Ratio Map of Star-forming Spaxels <marvin-plotting-niiha-map-starforming>
    • marvin-plotting-qualitative-colorbar
    • marvin-plotting-custom-map-mask

Default Plotting Parameters

MPL-5+
Property Type Bad Data Bitmasks Colormap Percentile Clip Symmetric Colorbar Minimum SNR
==================== ==================== ========= =============== ================== ===========
default UNRELIABLE, DONOTUSE linearlab 5, 95 False 1
velocities UNRELIABLE, DONOTUSE RdBu_r 10, 90 True 0a
velocity dispersions UNRELIABLE, DONOTUSE inferno 10, 90 False 1

a Velocities do not have a minimum SNR. This allows spaxels near the zero-velocity contour to be displayed, but users are cautioned that some spaxels could have arbitrarily low SNRs.

Note: MPL-4 uses the same default plotting parameters as MPL-5, except the Bad Data Bitmasks, which use bit 1 (roughly DONOTUSE) for all properties.

Masking

Spaxels with Low Signal-to-Noise

~marvin.utils.plot.map.mask_low_snr creates a mask of a map where the data is below a minimum signal-to-noise ratio.

from marvin.tools.maps import Maps
import marvin.utils.plot.map as mapplot
maps = Maps(plateifu='8485-1901')
ha = maps['emline_gflux_ha_6564']
low_snr = mapplot.mask_low_snr(value=ha.value, ivar=ha.ivar, snr_min=1)

Important: In 2.1.4, the call signature is low_snr_mask(value, ivar, snr_min). In version 2.2.0, this changes to mask_low_snr(value, ivar, snr_min).

Spaxels with Negative Values

~marvin.utils.plot.map.mask_neg_values creates a mask of a map where the values are negative. This is necessary to avoid erros when using a logarithmic colorbar.

from marvin.tools.maps import Maps
import marvin.utils.plot.map as mapplot
maps = Maps(plateifu='8485-1901')
ha = maps['emline_gflux_ha_6564']
neg_values = mapplot.mask_neg_values(value=ha.value)

Important: In 2.1.4, the call signature is log_colorbar_mask(value, log_cb). In version 2.2.0, this changes to mask_neg_values(value).

Set Title

~marvin.utils.plot.map.set_title sets the title of the axis object. You can directly specify the title or construct it from the property name (and channel name).

import marvin.utils.plot.map as mapplot
title = mapplot.set_title(title=None, property_name=ha.datamodel.name, channel=ha.datamodel.channel.name)

Reference/API

Module

marvin.utils.plot.map

Functions

marvin.utils.plot.map.ax_setup marvin.utils.plot.map.mask_low_snr marvin.utils.plot.map.mask_neg_values marvin.utils.plot.map.plot marvin.utils.plot.map.set_title