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I have a large dataframe (~500,000 observations) consisting of structured Twitter data (i.e. username, rewtweet counts, text) in RStudio. I want to run a text analysis on the tweets so I can extract observations that have one or more keywords in the tweet text.

I have uploaded my keywords as keywords_C <- c("climate change","climate","climatechange","global warming","globalwarming") . Tweet text is stored in my dataframe in a column labelled text.

How do I make a new dataframe containing only observations where one or more of the keywords are present in the text column? Alternatively, can I delete observations where the keywords are not present?

Added info:
My dataframe looks something like this...

 id_num,    follower_count,    text                                        ;

 123 ,      135  ,             Climate change is not science, it’s religion;

 456 ,      73   ,             Interesting article here from Reuters       ;

 789 ,      1367 ,             Our warming climate is danger #1!           ;

 345 ,      489  ,             New episode of blue planet!                 ; 

Using the keywords_C value, I'm hoping to write a code that will extract rows that contain the keywords and create a new dataframe. So in this example, the new dataframe would be...

 id_num,    follower_count,    text                                        ;

 123 ,      135  ,             Climate change is not science, it’s religion;

 789 ,      1367 ,             Our warming climate is danger #1!           ;

My dataframe is called NewCData

dput(droplevels(head(NewCData, 10)))

structure(list(timestamp = structure(c(1L, 3L, 2L, 6L, 4L, 4L, 

5L, 8L, 7L, 9L), .Label = c("2015-10-30 21:37:58", "2015-10-30 21:38:02", 

"2015-10-30 21:38:03", "2015-10-30 21:38:06", "2015-10-30 21:38:07", 

"2015-10-30 21:38:10", "2015-10-30 21:38:14", "2015-10-30 21:38:32", 

"2015-10-30 21:39:04"), class = "factor"), id_str = structure(c(1L, 

3L, 2L, 7L, 4L, 5L, 6L, 9L, 8L, 10L), .Label = c("660209050429186048", 

"660209067584016384", "660209072768212992", "660209083505504256", 

"660209086143688704", "660209087628578816", "660209102790914048", 

"660209119152893952", "660209195162206208", "660209325986549760"

), class = "factor"), user.id_str = structure(c(1L, 3L, 8L, 5L, 

5L, 2L, 4L, 6L, 9L, 7L), .Label = c("277335277", "32380087", 

"325105950", "33398863", "68956490", "808114195", "87712431", 

"90280824", "949996219"), class = "factor"), user.followers_count = structure(c(7L, 

2L, 8L, 4L, 4L, 3L, 6L, 9L, 5L, 1L), .Label = c("10212", "1062", 

"1389", "15227", "2214", "2851", "38", "4137", "55"), class = "factor"), 

    ideology = structure(c(2L, 4L, 3L, 9L, 9L, 5L, 8L, 6L, 1L, 

    7L), .Label = c("-0.309303177803536", "-0.393703659798908", 

    "-0.795976086971656", "-0.811321629152632", "-0.946143178314071", 

    "-1.16317298915931", "0.353843466445817", "1.09919837237897", 

    "2.29286233202781"), class = "factor"), text = structure(c(2L, 

    9L, 4L, 1L, 3L, 10L, 5L, 7L, 6L, 8L), .Label = c("Better Dead than Red! Bill Gates says that only socialism can save us ", 

    "Expert briefing on  #disarmament #SDGs @NMUN ", 

    "I see red people Bill Gates says that only socialism can save us from climate change ", 

    "RT: Oddly enough, some Republicans think climate change is real: Oddly enough,…  #UniteBlue ", 

    "Ted Cruz: ‘Climate change is not science, it’s religion’  via @glennbeck", 

    "This is an amusing headline: "Bill Gates says that only socialism can save us from climate change"", 

    "Unusual Weather Kills Gulf of Maine Cod : Discovery News #globalwarming  ", 

    "What do the remaining Republican candidates have to say about climate change? #FixGov", 

    "Who Uses #NASA Earth Science Data? He looks at impact of #aerosols on #climate #weather!", 

    "Why go for ecosystem basses conservation! #ClimateChange #Raajje #Maldives"

    ), class = "factor")), .Names = c("timestamp", "id_str", 

"user.id_str", "user.followers_count", "ideology", "text"), row.names = c(NA, 

10L), class = "data.frame")

You may use

new_df <- NewCData[with(NewCData, grepl(paste0("\b(?:",paste(keywords_C, collapse="|"),")\b"), text)),]

See the R demo online

The point here is to combine the keywords into a pattern like

b(?:climate change|climate|climatechange|global warming|globalwarming)b

It will match the words as whole words and if there is a match in the text column, the row will be returned, else, the row will get discarded.