“Astropy.io.fits”的版本间差异
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（创建页面，内容为“ >>> hdulist = fits.open('input.fits') >>> hdulist.info() ==header== *each element of an HDUList is an HDU object with .header and .data attributes, which can be…”） |
无编辑摘要 |
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==header== |
==header== |
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*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. |
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>> list(hdr.keys()) |
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>>> hdr['targname'] |
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*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)): |
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* FITS标准使用的特定结构关键字集随HDU类型的不同而不同,还有许多其他保留的关键字，例如用于数据缩放的关键字，或用于表的列属性的关键字，如FITS标准中所述。其中大多数都可以通过Column或HDU对象的属性访问，例如用HDU .name设置EXTVER的 EXTNAME或HDU.ver。结构关键字将作为通用操作的结果进行检查和/或更新。例如,关键字NAXIS*从数据形状(.data.shape)中设置，BITPIX从数据类型(.data.dtype)中设置,调用HDU的验证方法(PrimaryHDU.verify()),一些关键字可以自动修复。 |
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*It’s also possible to view a slice of the header: |
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===comment/hitory=== |
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*Another way to either update an existing card or append a new one is to use the Header.set() method: |
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>>> hdr['history'] = 'I updated this file 2/26/09' |
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>>> hdr['comment'] = 'Edwin Hubble really knew his stuff' |
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>>> hdr['comment'] = 'I like using HST observations' |
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>>> hdr['history'] |
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I updated this file 2/26/09 |
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>>> hdr['comment'] |
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Edwin Hubble really knew his stuff |
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I like using HST observations |
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>>> hdr['comment'][1] = 'I like using JWST observations' |
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>>> hdr['comment'] |
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Edwin Hubble really knew his stuff |
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I like using JWST observations |
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==fits table 的读与写== |
==fits table 的读与写== |
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*读 |
*读 |
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hdu = fits.open('SFH_LMC3_out.fits') |
hdu = fits.open('SFH_LMC3_out.fits') |
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hdu.info() #看看哪些hdu |
hdu.info() #看看哪些hdu |
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data=hdu[1].data |
data=hdu[1].data |
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cols=hdu[1].columns |
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data.columns #看看有那些列 |
data.columns #看看有那些列 |
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data.field(0) #读取第一列，也可以拿到列的名字，然后data['tag']读取 |
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Bage=data. Field('Age') |
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data[0] #第一行 |
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* 修改columns中某个keyword的值 |
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columns = fits.ColDefs(hdul[1].columns) |
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clumns1.change_attrib(col_name='DATA',attrib='format',new_value='8388608B') |
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*更新 |
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:可以使用**HDUList.flush()方法将自open()**以来所做的所有更改写回原始文件。**close()**方法将对以更新模式打开的FITS文件执行相同的操作: |
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with fits.open('original.fits', mode='update') as hdul: |
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# Change something in hdul. |
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hdul.flush() |
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==fits文件打开过多错误== |
==fits文件打开过多错误== |
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:*del hdu.data |
:*del hdu.data |
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:*hdu = fits.open(fits_name,memmap=False) #打开fits文件数目比较多的情况下 |
:*hdu = fits.open(fits_name,memmap=False) #打开fits文件数目比较多的情况下 |
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2023年7月9日 (日) 01:47的最新版本
>>> hdulist = fits.open('input.fits')
>>> hdulist.info()
header
>>> hdr=hdulist[0].header
>> list(hdr.keys())
>>> hdr['targname']
>>> header[:2] #只看前面两个
>>> hdr.set('observer', 'Edwin Hubble') #添加header
- FITS标准使用的特定结构关键字集随HDU类型的不同而不同,还有许多其他保留的关键字，例如用于数据缩放的关键字，或用于表的列属性的关键字，如FITS标准中所述。其中大多数都可以通过Column或HDU对象的属性访问，例如用HDU .name设置EXTVER的 EXTNAME或HDU.ver。结构关键字将作为通用操作的结果进行检查和/或更新。例如,关键字NAXIS*从数据形状(.data.shape)中设置，BITPIX从数据类型(.data.dtype)中设置,调用HDU的验证方法(PrimaryHDU.verify()),一些关键字可以自动修复。
comment/hitory
>>> hdr['history'] = 'I updated this file 2/26/09' >>> hdr['comment'] = 'Edwin Hubble really knew his stuff' >>> hdr['comment'] = 'I like using HST observations' >>> hdr['history'] I updated this file 2/26/09 >>> hdr['comment'] Edwin Hubble really knew his stuff I like using HST observations >>> hdr['comment'][1] = 'I like using JWST observations' >>> hdr['comment'] Edwin Hubble really knew his stuff I like using JWST observations
fits table 的读与写
- 读
hdu = fits.open('SFH_LMC3_out.fits')
hdu.info() #看看哪些hdu
data=hdu[1].data
cols=hdu[1].columns
data.columns #看看有那些列
data.field(0) #读取第一列，也可以拿到列的名字，然后data['tag']读取
data[0] #第一行
- 修改columns中某个keyword的值
columns = fits.ColDefs(hdul[1].columns) clumns1.change_attrib(col_name='DATA',attrib='format',new_value='8388608B')
- 写
from astropy.table import Table
t=Table([Bage,fzbin,Age_weight2],names=('Age','z','weights'))
t.write('SFH_LMC3_out.fits',format='fits')
- 更新
- 可以使用**HDUList.flush()方法将自open()**以来所做的所有更改写回原始文件。**close()**方法将对以更新模式打开的FITS文件执行相同的操作:
with fits.open('original.fits', mode='update') as hdul:
# Change something in hdul.
hdul.flush()
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')
fits文件打开过多错误
- [1]
- 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 [2],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