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Keys
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Keys

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Keys[key1val1,key2val2,…]

gives a list of the keys keyi in an association.

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Keys[{key1val1,key2val2,…}]

gives a list of the keyi in a list of rules.

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Keys[expr,h]

gives a list of keys in expr, wrapping each of them with head h before evaluation.

Details

Examples

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Basic Examples  (4)Summary of the most common use cases

Get the keys in an association:

In[1]:=1
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https://wolfram.com/xid/0y8w6c-bn4926
Out[1]=1

Get keys from a list of rules:

In[1]:=1
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https://wolfram.com/xid/0y8w6c-cxf7cl
Out[1]=1

Keys automatically threads over lists:

In[1]:=1
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https://wolfram.com/xid/0y8w6c-pfsehu
Out[1]=1

Wrap keys with Hold to prevent evaluation:

In[1]:=1
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https://wolfram.com/xid/0y8w6c-yipf
Out[1]=1

Properties & Relations  (5)Properties of the function, and connections to other functions

Keys are listed in the order of their appearance:

In[1]:=1
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https://wolfram.com/xid/0y8w6c-cj1o4h
Out[1]=1

Keys automatically threads over lists, but not associations:

In[1]:=1
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https://wolfram.com/xid/0y8w6c-llznyi
Out[1]=1

Keys returns time stamps for a TimeSeries input:

In[1]:=1
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https://wolfram.com/xid/0y8w6c-hnyssz
In[2]:=2
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https://wolfram.com/xid/0y8w6c-vk6a7a
Out[2]=2
In[3]:=3
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https://wolfram.com/xid/0y8w6c-7pf4lj
Out[3]=3

Keys of a Tabular object returns row keys if key columns are specified:

In[1]:=1
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https://wolfram.com/xid/0y8w6c-qkyqj6
Out[1]=1
In[2]:=2
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https://wolfram.com/xid/0y8w6c-dgd8l7
Out[2]=2

For multiple key columns:

In[3]:=3
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https://wolfram.com/xid/0y8w6c-qkcio9
Out[3]=3
In[4]:=4
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https://wolfram.com/xid/0y8w6c-tocgl2
Out[4]=4

For a Tabular object without key columns, Keys returns None:

In[1]:=1
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https://wolfram.com/xid/0y8w6c-wd656u
Out[1]=1
In[2]:=2
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https://wolfram.com/xid/0y8w6c-yfhrb9
Out[2]=2
Wolfram Research (2014), Keys, Wolfram Language function, https://reference.wolfram.com/language/ref/Keys.html (updated 2025).
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Wolfram Research (2014), Keys, Wolfram Language function, https://reference.wolfram.com/language/ref/Keys.html (updated 2025).

Text

Wolfram Research (2014), Keys, Wolfram Language function, https://reference.wolfram.com/language/ref/Keys.html (updated 2025).

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Wolfram Research (2014), Keys, Wolfram Language function, https://reference.wolfram.com/language/ref/Keys.html (updated 2025).

CMS

Wolfram Language. 2014. "Keys." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2025. https://reference.wolfram.com/language/ref/Keys.html.

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Wolfram Language. 2014. "Keys." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2025. https://reference.wolfram.com/language/ref/Keys.html.

APA

Wolfram Language. (2014). Keys. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Keys.html

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Wolfram Language. (2014). Keys. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Keys.html

BibTeX

@misc{reference.wolfram_2025_keys, author="Wolfram Research", title="{Keys}", year="2025", howpublished="\url{https://reference.wolfram.com/language/ref/Keys.html}", note=[Accessed: 16-April-2025 ]}

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@misc{reference.wolfram_2025_keys, author="Wolfram Research", title="{Keys}", year="2025", howpublished="\url{https://reference.wolfram.com/language/ref/Keys.html}", note=[Accessed: 16-April-2025 ]}

BibLaTeX

@online{reference.wolfram_2025_keys, organization={Wolfram Research}, title={Keys}, year={2025}, url={https://reference.wolfram.com/language/ref/Keys.html}, note=[Accessed: 16-April-2025 ]}

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@online{reference.wolfram_2025_keys, organization={Wolfram Research}, title={Keys}, year={2025}, url={https://reference.wolfram.com/language/ref/Keys.html}, note=[Accessed: 16-April-2025 ]}