Differences between revisions 22 and 23

For loops

a)

   1 a = [range(0,4)]
   2 for item in a:
   3          b = item * 4  
   4          b.sort() 
   5          c = item * 4 
   6          d = [b,c] 
   7          print d

Data types

A=dict([('a',1),('b',2)])

Please specify the data types:

A is a ...
'a' is a ...
1 is a ...
('a',1) is a ...
[('a',1),('b',2)] is a ...

Provide an alternative way to assign A

Scipy numeric types

from scipy import *

One byte consists of eight bit and covers the value range of 0..255 (uint8, unsigned integer) or -128..127.

   1 b=int8(128)
   2 -128 # Invalid range
   3 
   4 b.nbytes
   5 1

a)

What is the value range of the following types and how many bytes are allocated in the memory?

bool8
uint8, int8
uint16, int16
uint32, int32
uint64, uint64

Solution:

b)

How many bytes are allocated in the memory by these floating point types?

float32, float64, float96
complex64, complex128, complex192

Solution:

Data structures

a)

   1 D={'A':array(range(10)),'B':array(range(10))+1}

Which keys contains the dictionary D
Get the keys with the method D.keys()
Display all values of D using the method .values()
Display array A
Display the elements 3:6 of arrays B
Set this elements to 0
Insert a new key-values pair C:array(range(0,10,-1)) into D

Solution:

Reading and practicing

Install python and ipython on your computer and read through the tutorial which comes with the documentation. There are translations in other languages:

-  ⇤ ← Revision 22 as of 2008-11-17 14:17:40 → 
  Size: 2732
  Editor: KorFreier
  Comment:
+   ← Revision 23 as of 2008-11-17 14:18:48 → ⇥
  Size: 2207
  Editor: anonymous
  Comment:
-Deletions are marked like this.
+Additions are marked like this.
 Line 7:
-{{{
#!python
-Line 10:
+Line 8:
-for i in range(0,4,1):
     print i
-Line 13:
+Line 9:
-
1
2
3
+{{{#!python
a = [range(0,4)]
for item in a:
         b = item * 4  
         b.sort() 
         c = item * 4 
         d = [b,c] 
         print d
 Line 18:
- * Insert an expression in {{{...}}} to get the results.

Solution:

== b) ==
{{{
0 0
0 1
0 2
0 3
1 0
1 1
1 2
1 3
2 0
2 1
2 2
2 3
3 0
3 1
3 2
3 3
}}}
 * What are the corresponding loops?

Solution:

In [51]: a='0'
In [52]: b='1'
In [53]: 4*a+4*b

Out[53]: '00001111'
-----

In [44]: a=0,1,2,3

In [45]: a*4

Out[45]: (0,1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 0)

Second Solution (in einer Schleife):

a = [range(0,4)]

for item in a:

         b = item * 4  

          b.sort() 

           c = item * 4 

            d = [b,c] 

             print d