Improve projection tutorials (#816)

Style changes and fixes in the example projection gallery files.

examples/projections/azim/azim_equidistant.py

@@ -11,13 +11,13 @@
 **e**\ *lon0/lat0*\ [*/horizon*]\ */scale* or
 **E**\ *lon0/lat0*\ [*/horizon*]\ */width*
 
-The projection type is set with **e** or **E**, *lon0/lat0* specifies the projection
-center, and the optional parameter *horizon* specifies the max distance to the
+The projection type is set with **e** or **E**. *lon0/lat0* specifies the projection
+center, and the optional parameter *horizon* specifies the maximum distance to the
 projection center (i.e. the visibile portion of the rest of the world map) in
 degrees <= 180° (default 180°). The size of the figure is set by *scale* or *width*.
 """
 import pygmt
 
 fig = pygmt.Figure()
-fig.coast(projection="E-100/40/4.5i", region="g", frame="g", land="gray")
+fig.coast(projection="E-100/40/15c", region="g", frame="g", land="gray")
 fig.show()

examples/projections/azim/azim_general_perspective.py

@@ -20,15 +20,15 @@
 degrees). *Width* and *Height* describe the viewport angle in degrees, and *scale*
 or *width* determine the size of the figure.
 
-The example shows the coast of northern europe viewed from 250 km above sea
+The example shows the coast of Northern Europe viewed from 250 km above sea
 level looking 30° from north at a tilt of 45°. The height and width of the
 viewing angle is both 60°, which imitates viewing with naked eye.
 """
 import pygmt
 
 fig = pygmt.Figure()
 fig.coast(
-    projection="G4/52/250/30/45/0/60/60/5i",
+    projection="G4/52/250/30/45/0/60/60/12c",
     region="g",
     frame=["x10g10", "y5g5"],
     land="gray",

examples/projections/azim/azim_general_stereographic.py

@@ -13,12 +13,12 @@
 or **S**\ *lon0/lat0*\ [*/horizon*\]\ */width*
 
 The projection type is set with **s** or **S**. *lon0/lat0* specifies the
-projection center, the optional *horizon* parameter specifies the max distance from
+projection center, the optional *horizon* parameter specifies the maximum distance from
 projection center (in degrees, < 180, default 90), and the *scale* or *width* sets the
 size of the figure.
 """
 import pygmt
 
 fig = pygmt.Figure()
-fig.coast(region="4/14/52/57", projection="S0/90/4.5i", frame="ag", land="gray")
+fig.coast(region=[4, 14, 52, 57], projection="S0/90/12c", frame="ag", land="gray")
 fig.show()

examples/projections/azim/azim_gnomonic.py

@@ -3,7 +3,7 @@
 ========
 
 The point of perspective of the gnomonic projection lies at the center of the
-earth. As a consequence great circles (orthodromes) on the surface of the earth
+earth. As a consequence great circles (orthodromes) on the surface of the Earth
 are displayed as straight lines, which makes it suitable for distance estimation
 for navigational purposes. It is neither conformal nor equal-area and the
 distortion increases greatly with distance to the projection center. It follows
@@ -14,12 +14,12 @@
 or **F**\ *lon0/lat0*\ [*/horizon*\ ]\ */width*
 
 **f** or **F** specifies the projection type, *lon0/lat0* specifies the projection
-center, the optional parameter *horizon* specifies the max distance from projection
+center, the optional parameter *horizon* specifies the maximum distance from projection
 center (in degrees, < 90, default 60), and *scale* or *width* sets the size of the
 figure.
 """
 import pygmt
 
 fig = pygmt.Figure()
-fig.coast(projection="F-90/15/4.5i", region="g", frame="20g20", land="gray")
+fig.coast(projection="F-90/15/12c", region="g", frame="20g20", land="gray")
 fig.show()

examples/projections/azim/azim_lambert.py

@@ -11,11 +11,11 @@
 or **A**\ *lon0/lat0*\ [*/horizon*\ ]\ */width*
 
 **a** or **A** specifies the projection type, and *lon0/lat0* specifies the projection
-center, *horizon* specifies the max distance from projection center (in degrees,
+center, *horizon* specifies the maximum distance from projection center (in degrees,
 <= 180, default 90), and *scale* or *width* sets the size of the figure.
 """
 import pygmt
 
 fig = pygmt.Figure()
-fig.coast(region="g", frame="afg", land="gray", projection="A30/-20/60/8i")
+fig.coast(region="g", frame="afg", land="gray", projection="A30/-20/60/12c")
 fig.show()

examples/projections/azim/azim_orthographic.py

@@ -12,11 +12,11 @@
 or **G**\ *lon0/lat0*\ [*/horizon*\ ]\ */width*
 
 **g** or **G** specifies the projection type, *lon0/lat0* specifies the projection
-center, the optional parameter *horizon* specifies the max distance from projection
+center, the optional parameter *horizon* specifies the maximum distance from projection
 center (in degrees, <= 90, default 90), and *scale* and *width* set the figure size.
 """
 import pygmt
 
 fig = pygmt.Figure()
-fig.coast(projection="G10/52/4.5i", region="g", frame="g", land="gray")
+fig.coast(projection="G10/52/12c", region="g", frame="g", land="gray")
 fig.show()

examples/projections/conic/conic_albers.py

@@ -23,6 +23,6 @@
 fig = pygmt.Figure()
 # Use the ISO country code for Brazil and add a padding of 2 degrees (+R2)
 fig.coast(
-    projection="B-55/-15/-25/0/8i", region="BR+R2", frame="afg", land="gray", borders=1
+    projection="B-55/-15/-25/0/12c", region="BR+R2", frame="afg", land="gray", borders=1
 )
 fig.show()

examples/projections/conic/conic_equidistant.py

@@ -25,5 +25,4 @@
     water="lightblue",
     frame="afg",
 )
-
 fig.show()

examples/projections/cyl/cyl_cassini.py

@@ -20,5 +20,5 @@
 
 fig = pygmt.Figure()
 # Use the ISO code for Madagascar (MG) and pad it by 2 degrees (+R2)
-fig.coast(projection="C47/-19/8i", region="MG+R2", frame="afg", land="gray", borders=1)
+fig.coast(projection="C47/-19/12c", region="MG+R2", frame="afg", land="gray", borders=1)
 fig.show()

examples/projections/cyl/cyl_mercator.py

@@ -15,7 +15,7 @@
 **m**\ [*lon0[/lat0]*]\ */scale* or **M**\ [*lon0*][*/lat0*]\ */width*
 
 The projection is set with **m** or **M**. The central meridian is set with the
-option *lon0* and the standard parallel is set with the option *lat0*.
+optional *lon0* and the standard parallel is set with the optional *lat0*.
 The figure size is set with *scale* or *width*.
 """
 import pygmt

examples/projections/cyl/cyl_stereographic.py

@@ -28,5 +28,5 @@
 import pygmt
 
 fig = pygmt.Figure()
-fig.coast(region="g", frame="afg", land="gray", projection="Cyl_stere/30/-20/8i")
+fig.coast(region="g", frame="afg", land="gray", projection="Cyl_stere/30/-20/12c")
 fig.show()

examples/projections/nongeo/cartesian_linear.py

@@ -2,20 +2,20 @@
 Cartesian linear
 ================
 
-``Xwidth/[height]``: Give the ``width`` of the figure and the optional argument ``height``.
+**X**\ *width*/[*height*]: Give the *width* of the figure and the optional *height*.
 """
 import pygmt
 
 fig = pygmt.Figure()
 fig.plot(
-    # The ``x`` and ``y`` parameters are used to plot lines on the figure.
+    # The ``x`` and ``y`` arguments determine the coordinates of lines
     x=[3, 9, 2],
     y=[4, 9, 37],
     pen="3p,red",
     # ``region`` sets the x and y ranges or the Cartesian figure.
     region=[0, 10, 0, 50],
-    # The argument ``WSne`` is passed to ``frame`` to put axis labels only on the left and bottom axes.
     projection="X15c/10c",
+    # ``WSne`` is passed to ``frame`` to put axis labels only on the left and bottom axes.
     frame=["af", "WSne"],
 )
 fig.show()

examples/projections/nongeo/cartesian_logarithmic.py

@@ -2,9 +2,9 @@
 Cartesian logarithmic
 =====================
 
-``xwidth[l]/[height[l]]``: Give the ``width`` of the figure and the optional argument \
-``height``. The axis or axes with a logarithmic transformation requires ``l`` after
-its size argument.
+**X**\ *width*\ [**l**]/[*height*\ [**l**]]: Give the *width* of the figure and
+the optional *height*. The axis or axes with a logarithmic transformation requires
+**l** after its size argument.
 """
 import numpy as np
 import pygmt

examples/projections/nongeo/polar.py

@@ -2,7 +2,7 @@
 Polar
 =====
 
-``Pwidth``: Give the ``width`` of the figure.
+**P**\ *width*: Give the *width* of the figure.
 
 """
 import pygmt