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************************
SSWIDL/sunpy Cheat Sheet
************************
`SolarSoft (SSWIDL) <https://sohowww.nascom.nasa.gov/solarsoft/>`__ is a popular IDL software library for solar data analysis, and in fact, many parts of sunpy are inspired by data structures and functions in SSWIDL.
Though IDL and Python are very different it sometimes helps to consider how to translate simple tasks between the two languages.
The primary packages which provide much of the functionality for scientific data analysis in Python are NumPy and SciPy.
In the following we assume that those packages are available to you and that you have imported Numpy with the following import statement:
.. code-block:: python
import numpy as np
import scipy as sp
In the following examples, ``a`` and ``b`` could be arrays.
For python the arrays must be numpy arrays which can be created simply through:
.. code-block:: python
np.array(a)
where a is a Python list of numbers.
**Relational Operators**
========= ========
IDL Python
========= ========
a EQ b a == b
a LT b a < b
a GT b a > b
a GE b a >= b
a LE b a <= b
a NE b a != b
========= ========
**Logical Operators**
========= ========
IDL Python
========= ========
a and b a and b
a or b a or b
========= ========
**Math Functions**
========= ========
IDL Python
========= ========
cos(a) np.cos(a)
alog(a) np.log(a)
alog10(a) np.alog(a)
exp(a) np.exp(a)
========= ========
**Math Constants**
========= ========
IDL Python
========= ========
!pi np.pi
exp(1) np.e
========= ========
**Arrays Sequences**
============ ========
IDL Python
============ ========
indgen(10) np.arange(0,10)
findgen(10) np.arange(0,10,dtype=np.float)
============ ========
**Array Creation**
============= =========
IDL Python
============= =========
dblarr(3,5) np.zeros((3,5))
intarr(3,5) np.zeros((3,5),dtype=np.int)
dblarr(3,5)+1 np.ones((3,5))
intarr(3,5)+9 np.zeros((3,5),dtype=np.int) + 9
boolarr(10) np.zeros(10,dtype=bool)
identity(3) np.identity(3)
============= =========
Many more examples can be found on this `NumPy for IDL users page <https://mathesaurus.sourceforge.net/idl-numpy.html>`__
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