“Astropy”的版本间差异
跳到导航
跳到搜索
无编辑摘要 |
无编辑摘要 |
||
| （未显示同一用户的5个中间版本） | |||
| 第1行： | 第1行： | ||
*很好的教程网站 [https://learn.astropy.org/] |
*很好的教程网站 [https://learn.astropy.org/] |
||
:比如星际红化的 [https://learn.astropy.org/tutorials/color-excess.html] |
:比如星际红化的 [https://learn.astropy.org/tutorials/color-excess.html] |
||
| ⚫ | |||
[http://docs.astropy.org/en/stable/io/fits/] |
|||
==io== |
|||
>>> hdulist = fits.open('input.fits') |
|||
| ⚫ | |||
>>> hdulist.info() |
|||
* ascii文件：Table格式，支持ecsv文件直接读入table |
|||
===header=== |
|||
*each element of an HDUList is an HDU object with .header and .data attributes, which can be used to access the header and data portions of the HDU. |
|||
>>> hdulist[0].header['targname'] |
|||
*To see the entire header as it appears in the FITS file (with the END card and padding stripped), simply enter the header object by itself, or print(repr(header)): |
|||
*It’s also possible to view a slice of the header: |
|||
>>> header[:2] |
|||
*Another way to either update an existing card or append a new one is to use the Header.set() method: |
|||
>>> prihdr.set('observer', 'Edwin Hubble') |
|||
===fits table 的读与写=== |
|||
*写 |
|||
from astropy.table import Table |
|||
t=Table([Bage,fzbin,Age_weight2],names=('Age','z','weights')) |
|||
t.write('SFH_LMC3_out.fits',format='fits') |
|||
*读 |
|||
hdu = fits.open('SFH_LMC3_out.fits') |
|||
hdu.info() #看看哪些hdu |
|||
data=hdu[1].data |
|||
data.columns #看看有那些列 |
|||
Bage=data.field('Age') |
|||
===fits文件打开过多错误=== |
|||
* [https://docs.astropy.org/en/stable/io/fits/appendix/faq.html#i-am-opening-many-fits-files-in-a-loop-and-getting-oserror-too-many-open-files] |
|||
* fits.close() |
|||
* 可能还根系统设置有关 |
|||
ulimit -a |
|||
ulimit -n 100000 |
|||
vim /etc/security/limits.conf |
|||
* 把python的软限制编程硬限制,参见 [https://bbs.huaweicloud.com/blogs/108323],下面方法貌似也不管用 |
|||
import resource |
|||
soft, hard = resource.getrlimit(resource.RLIMIT_NOFILE) |
|||
resource.setrlimit(resource.RLIMIT_NOFILE, (hard, hard)) |
|||
*lsof -p 进程id > openfiles.log命令，获得当前占用句柄的全部详情进行分析 |
|||
* 实测这两个效果不好（python 3.8） |
|||
:*del hdu.data |
|||
:*hdu = fits.open(fits_name,memmap=False) #打开fits文件数目比较多的情况下 |
|||
==fits image读写== |
|||
n = np.arange(100.0) |
|||
hdu = fits.PrimaryHDU(n) |
|||
hdu.writeto('new2.fits') |
|||
hdu.writeto('new2.fits') |
|||
*如果超过一个hdu |
|||
>>> hdul = fits.HDUList([hdu]) |
|||
>>> hdul.writeto('new1.fits') |
|||
==astrometry== |
==astrometry== |
||
| 第60行： | 第12行： | ||
>>> c = SkyCoord(ra=ra1*u.degree, dec=dec1*u.degree) |
>>> c = SkyCoord(ra=ra1*u.degree, dec=dec1*u.degree) |
||
>>> catalog = SkyCoord(ra=ra2*u.degree, dec=dec2*u.degree) |
>>> catalog = SkyCoord(ra=ra2*u.degree, dec=dec2*u.degree) |
||
>>> idx, d2d, d3d = c.match_to_catalog_sky(catalog) |
>>> idx, d2d, d3d = c.match_to_catalog_sky(catalog) #d3d是假设距离为1的地方的3维距离，因此是以弧度为单位 |
||
>>> sel=np.where(d2d.degree < 0.00002) |
>>> sel=np.where(d2d.degree < 0.00002) |
||
>>> Nsel=len(sel[0]) |
|||
>>> print(ra1[sel][0],ra2[idx[sel][0]) |
|||
*算出任意两点之间距离向量的PA角，还有中点坐标[https://docs.astropy.org/en/stable/coordinates/matchsep.html] |
|||
==宇宙学== |
==宇宙学== |
||
2024年7月12日 (五) 14:24的最新版本
- 很好的教程网站 [1]
- 比如星际红化的 [2]
io
- astropy.io.fits
- ascii文件：Table格式，支持ecsv文件直接读入table
astrometry
- match 两个星表
>>> from astropy.coordinates import SkyCoord >>> from astropy import units as u >>> c = SkyCoord(ra=ra1*u.degree, dec=dec1*u.degree) >>> catalog = SkyCoord(ra=ra2*u.degree, dec=dec2*u.degree) >>> idx, d2d, d3d = c.match_to_catalog_sky(catalog) #d3d是假设距离为1的地方的3维距离，因此是以弧度为单位 >>> sel=np.where(d2d.degree < 0.00002) >>> Nsel=len(sel[0]) >>> print(ra1[sel][0],ra2[idx[sel][0])
- 算出任意两点之间距离向量的PA角，还有中点坐标[3]
宇宙学
http://docs.astropy.org/en/stable/cosmology/
- 从红移到年龄
>>>from astropy.cosmology import FlatLambdaCDM >>>cosmo = FlatLambdaCDM(H0=70, Om0=0.3)
>>> lum_dis=cosmo.luminosity_distance(redshift) #计算光度距离
- 从年龄到红移
>>> import astropy.units as u >>> from astropy.cosmology import z_at_value >>> z_at_value(cosmos.age, 2 * u.Gyr)
单位转换
dL=lum_dis.to(u.cm)