473,594 Members | 2,651 Online
Bytes | Software Development & Data Engineering Community
+ Post

Home Posts Topics Members FAQ

fill in 3D array

Hi,

I am a python newbie, trying to convert my IDL scripts to python. I am
kind of stuck at the moment. I am reading in a 1-D data file with 2000
data points. I need to put them in a 3-D array with size [10,10,20]. I
have defined the field array as arr = zeros((10,10,20 )) but don't know
how to read the data into the array.

Also, I need to extract a slice of a 3-D array and tried a =
array_name(:,:, 20) but that didn't work.

Thanks,
Kim
Jul 24 '08 #1
3 2523
kn********@gmai l.com wrote:
Hi,

I am a python newbie, trying to convert my IDL scripts to python. I am
kind of stuck at the moment. I am reading in a 1-D data file with 2000
data points. I need to put them in a 3-D array with size [10,10,20]. I
have defined the field array as arr = zeros((10,10,20 )) but don't know
how to read the data into the array.
I assume that you are using numpy. Use numpy.fromfile( ) and the .reshape()
method. Assuming that your file is ASCII with numbers separated by whitespace:

import numpy
arr = numpy.fromfile( thefilename, sep=' ').reshape((10, 10,20))

There is no need, in this case, to create an array before reading the data.
Also, I need to extract a slice of a 3-D array and tried a =
array_name(:,:, 20) but that didn't work.
Python uses [] brackets for indexing, not ().

arr[:,:,20]

--
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco

Jul 24 '08 #2
On Jul 23, 9:18 pm, Robert Kern <robert.k...@gm ail.comwrote:
knielse...@gmai l.com wrote:
Hi,
I am a python newbie, trying to convert my IDL scripts to python. I am
kind of stuck at the moment. I am reading in a 1-D data file with 2000
data points. I need to put them in a 3-D array with size [10,10,20]. I
have defined the field array as arr = zeros((10,10,20 )) but don't know
how to read the data into the array.

I assume that you are using numpy. Use numpy.fromfile( ) and the .reshape()
method. Assuming that your file is ASCII with numbers separated by whitespace:

import numpy
arr = numpy.fromfile( thefilename, sep=' ').reshape((10, 10,20))

There is no need, in this case, to create an array before reading the data.
Also, I need to extract a slice of a 3-D array and tried a =
array_name(:,:, 20) but that didn't work.

Python uses [] brackets for indexing, not ().

arr[:,:,20]

--
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco
Thanks, working like a charm.
Jul 24 '08 #3
kn********@gmai l.com wrote:
On Jul 23, 9:18 pm, Robert Kern <robert.k...@gm ail.comwrote:
>knielse...@gma il.com wrote:
>>Hi,
I am a python newbie, trying to convert my IDL scripts to python. I am
kind of stuck at the moment. I am reading in a 1-D data file with 2000
data points. I need to put them in a 3-D array with size [10,10,20]. I
have defined the field array as arr = zeros((10,10,20 )) but don't know
how to read the data into the array.
I assume that you are using numpy. Use numpy.fromfile( ) and the .reshape()
method. Assuming that your file is ASCII with numbers separated by whitespace:

import numpy
arr = numpy.fromfile( thefilename, sep=' ').reshape((10, 10,20))

There is no need, in this case, to create an array before reading the data.
>>Also, I need to extract a slice of a 3-D array and tried a =
array_name(:, :,20) but that didn't work.
Python uses [] brackets for indexing, not ().

arr[:,:,20]

Thanks, working like a charm.
Great. If you have more numpy questions, you will probably want to ask them on
the numpy mailing list instead of here.

http://www.scipy.org/Mailing_Lists

--
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco

Jul 24 '08 #4

This thread has been closed and replies have been disabled. Please start a new discussion.

Similar topics

0
3914
by: Erwin Radermacher | last post by:
Hello dear PHP users, I have a form with text boxes and a dropdown menu with names of cities The adjacent textbox fills by the help of a Javascript function. My question is, how to realize the purpose of filling the adjacent texbox for zip values. Or say it otherwise: how to transfer an array, filled with php to a Javascript function.
5
2631
by: Fabio Papa | last post by:
Hi, I am fairly new to programming and and even newer to dotnet. I appoligise in advance if this is a dumb questions, and I would appreciate if you could answer it anyways. :) I am writing a windows service wich sends emails to customers at a specific time. My app retrieves cities and the city's associated time from a database, waits until the specified time for each city and sends out the appropriate emails. Below is some code that is...
5
6216
by: Joe C | last post by:
I'm a hobbiest, and made the forray into c++ from non-c type languages about a year ago. I was "cleaning up" some code I wrote to make it more "c++ like" and have a few questions. I'm comfortable using new/delete when dealing with arrays, and, so-far haven't used the STL (eg vectors) very much when dealing with POD. I'm using a class to dump files into. The class puts the file data into a 32-bit array, then offers both 32-bit and char*...
12
6386
by: ma740988 | last post by:
I've allocated 4K memory and I'd like to use std::fill to fill each 1K with a different value. Note: I could easily use a vector/deque but I'm interested in a C style array. int main() { int const max = 0x1000; int *ptr_mem = new int ; int initial(1); for ( int idx(0); idx < 4; ++idx )
19
3975
by: Alex | last post by:
Hello list This question has probably already been asked, but let me ask again I have a mysql database to which I connect with my php scripts. The database contains articles. Name, Unit_Price and Reference Now my client needs to order 5 items, click a button and a table with 5 lines and 3 columns appears (until now easy)
14
8320
by: romayankin | last post by:
Hello All, I'm writing cross-platform code so i'm bound to standards. Here is the code I have: ~~~~~~~~~~~~~~~~~~ double **mx = new double*; for(int i = 0; i < col - 1; i++) { mx = new double; sizeOfMx += sizeof(double) * row; }
2
21117
by: cpisz | last post by:
I saw that using std::fill was the way to go for setting all elements of an array to some value in one foul swoop. However when I tryed it I am getting an error. Can I only use this for vectors or can I use it for a regular array? what I called: std::fill(m_start_times, m_start_times, 0); error:
0
1744
by: dprjessie | last post by:
Hello, I am a Web programmer and I'm working on my first desktop application as a favor for a friend. I'm sure I have a stupid error here, but there is no error being thrown so I can't figure out what is wrong. I have code that reads an excel file and fills a datagridview and it works just fine. It is also supposed to fill a database though and that is not working. The executeNonQuery command is returning a 1 which as I understand, means it has...
1
2747
by: Gennaro Prota | last post by:
Hi, I have the following function template template< typename T, std::size_t n > void secure_fill( volatile T ( &arr ), const T & value = T() ) { for( std::size_t i( 0 ); i < n; ++i ) { arr = value;
1
3456
by: bytesFTW99 | last post by:
I have been struggling with this for some time can anyone help out? just trying to have 3 dropdown boxes that fill depending on what is selected, then in some cases click a button and have the second set of 3 dropdown boxes be filled with the same values. thank you <head> <SCRIPT LANGUAGE="JavaScript" type="text/javascript"> var firstChoice2 = 0; var secondChoice2 = 0;
0
7941
marktang
by: marktang | last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However, people are often confused as to whether an ONU can Work As a Router. In this blog post, we’ll explore What is ONU, What Is Router, ONU & Router’s main usage, and What is the difference between ONU and Router. Let’s take a closer look ! Part I. Meaning of...
0
8246
Oralloy
by: Oralloy | last post by:
Hello folks, I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>". The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed. This is as boiled down as I can make it. Here is my compilation command: g++-12 -std=c++20 -Wnarrowing bit_field.cpp Here is the code in...
0
8368
jinu1996
by: jinu1996 | last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth. The Art of Business Website Design Your website is...
1
8000
by: Hystou | last post by:
Overview: Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows Update option using the Control Panel or Settings app; it automatically checks for updates and installs any it finds, whether you like it or not. For most users, this new feature is actually very convenient. If you want to control the update process,...
1
5738
isladogs
by: isladogs | last post by:
The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM). In this session, we are pleased to welcome a new presenter, Adolph Dupré who will be discussing some powerful techniques for using class modules. He will explain when you may want to use classes instead of User Defined Types (UDT). For example, to manage the data in unbound forms. Adolph will...
0
3854
by: TSSRALBI | last post by:
Hello I'm a network technician in training and I need your help. I am currently learning how to create and manage the different types of VPNs and I have a question about LAN-to-LAN VPNs. The last exercise I practiced was to create a LAN-to-LAN VPN between two Pfsense firewalls, by using IPSEC protocols. I succeeded, with both firewalls in the same network. But I'm wondering if it's possible to do the same thing, with 2 Pfsense firewalls...
0
3895
by: adsilva | last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
1
2383
by: 6302768590 | last post by:
Hai team i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system
0
1205
bsmnconsultancy
by: bsmnconsultancy | last post by:
In today's digital era, a well-designed website is crucial for businesses looking to succeed. Whether you're a small business owner or a large corporation in Toronto, having a strong online presence can significantly impact your brand's success. BSMN Consultancy, a leader in Website Development in Toronto offers valuable insights into creating effective websites that not only look great but also perform exceptionally well. In this comprehensive...

By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use.

To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page.